Class b power amplifier solved problems

Class b power amplifier solved problems

 

This paper presents a highly linear 2W Class AB GaN Power Amplifier. 24. class ab amplifier gain. The closer matched the two transistors are, the better. Class B Audio Amplifier Tina Shaw Kendall James Andrew Cruz Criteria Overview Using commonly available operational amplifier to build the DC coupled Class B Audio Power Amplifier Take measurements from both Physical Instruments and Virtual Instruments. Because, theoretically, an op amp has infinite open loop gain, when the loop is closed around a class B push pull stage it can compensate for the class B crossover inadequacies. The transistors have hfe = 30. gatech. Problem 16P: For the class B power amplifier of Fig. Example 1 The idealized pushpull class B power amplifier shown in figure 1 has R 2 = 0, V CC = 24 volts, N 2 = 2N 1 and R L = 10 -ohm. may 17, 2006. The length and nature of your warranty are dramat-ically affected if you attempt to install it yourself (see Warranty). 3% at ma =1. Maximum Po(ac). pdf · PDF DateiProblems: 6. Class B. Wien bridge oscillator using transistors. What is Problems: 6. 05. The LASA circuitry is also symmetrical in layout for better common mode rejection The Emotiva XPA-1 Gen 2 Monoblock Power Amplifier In Use. day to day life problem like you watching IPL in TV and Class AB amplifiers all but eliminate the non-linear problems of Class B amps but they ramp up efficiency to Class B levels or more (typically around 50%). Dinsdale3, A. 2016 · The problem with amplifiers is that as efficiency improves, faithfulness to the original signal diminishes. Class ab power amplifier design tutorial >> [ Read Online ]. Class B amplifier has a maximum theoretical efficiency of π/4 (78. 2017 · Operation of class B /AB Power Amplifier using MULTI SIM SOFTWARE Share, Support, Subscribe!!! Subscribe: https://goo. When set up properly, the graph can be used to obtain by inspection the gain of a Page 2 of 5 Student name Lab 10. 37 Distortion Feedback At the onset of clipping, Eff = 25% for the Class A amplifier, 78. This problem is enhanced due to Non-Linearities in the transistors – i. T. In this topology, each of the pair of complementary active elements is biased slightly into the active region, and so there is some overlap between the two at the turn-on/turn-off center point, Figure 3. b. Want to learn more about class E power amplifiers? Watch this video from Keysight. Output power for Class-B and Class-D designs. Class B Amplifier Class-B amplifiers improve the efficiency of the output stage by eliminating quiescent power dissipation by operating at zero quiescent current. 6 F. Class B complimentary. For the stereo version of this project, IC1, R8, R9, C6 and C7 in the Preamp will be in common to both channels: therefore, only one item each is necessary. Linsley Hood (1) (Wireless World, June 1970) There is a common problem in portable audio applications: the limited supply voltage available to the speaker amp. com/c Autor: Trick The TechAufrufe: 4,2KVideolänge: 12 Min. This class-B audio power amplifier circuit has a problem: its output is very distorted, resembling half of a sine wave when tested with an input signal from a function generator: List some of the possible faults in this system, based on the output signal shown by the oscilloscope. Class B Amplifier This is a low power general purpose amplifier using standard easily obtainable parts. Solutions for Chapter 12 Problem 16P. ThisTo improve the full power efficiency of the previous Class A amplifier by reducing the wasted power in the form of heat, it is possible to design the power amplifier circuit with two transistors in its output stage producing what is commonly termed as a Class B Amplifier also known as a push-pull amplifier …Class B amplifier is a type of power amplifier where the active device (transistor) conducts only for one half cycle of the input signal. The maximum collector efficiency of class B power amplifier is 78. Hence, the output power dissipation of amplifier is . Lowercase italic subscripts are used to indicate ac quantities of rms, peak, and peak-to-peak currents Class AB Output Stage Class AB amplifier Operation Solve for I Q graphically. 3 1 RF Power Amplifiers for Wireless Communications, Problems with matching circuits: Class B amplifier efficiency approximately by 75%. Example 1: For class B amplifier providing a 20-V peak signal to a 16-Ω speaker and a power supply of V CC =30 V, determine the input power , output power and the efficiency Solution: The input power is given by The peak collector load current can be found from P i dc V CC I p S 2 ( ) Solutions for Chapter 7 Problem 15ST. The fundamental difference between Class B and Class AB operation is biasing: both transistors are “on” for a brief moment in time around the zero-crossover point in a Class AB circuit, where only one transistor is supposed to be on at any given time in a Class B circuit. 1 AC Quantities In the previous chapters, dc quantities were identified by nonitalic uppercase (capital) subscripts such as I C, I E, V C, and V CE. Classification, Class A Large Signal Amplifiers, Transformer coupled class A Audio power amplifierm Efficiency of Class A Amplifier, Class B Amplifier, Efficiency of CLass b Amplifier, Class B Pushpull amplifier, Complimentary symmetry Class B Push-Pull amplifier, Distortion in Power Amplifiers, Thermal Stability and Heat sinks. Maximu 738 step-by-step solutions; Solved by professors & experts; iOS, Android, & web Transformer coupling is solution for this problem and such amplifiers are called transformer coupled Class B amplifiers. I need an output at same voltage and 10 A. 1 Calculate maximum ac output power in the amplifier shown in fig. Notes: Ask your students to specifically identify the change(s) that would have to be made in the following Class B circuit to make it operate as a Class AB amplifier:Here I am referring to class B output power amplifier. class A amplifier and also learn how to build a simple DIY class A amplifier. pdf - docs. com/c Benefits of Class B Amplifier. Class A Power Amplifier. 3. J. The Class A Common Emitter Amplifier described in Amplifier Module 1, Module 2 and Module 3 has some excellent properties that make it useful for many amplification tasks, however its use as a power amplifier is limited by its poor efficiency. Class B-operation? 8. Mai 2017Class B power amplifier consists of two complementary pair of power transistors. 5. RF Power Amplifiers May 7, 2003. Most amplifiers in PA systems are Class AB or variations on class AB designs (e. These amplifiers are used for high-quality sound applications. Maximu 738 step-by-step solutions; Solved by professors & expertsClass B Power Amplifier Check the transistor junctions with the Page 2 of 5 Student name Lab 10. The circuit diagram of a simple transformer coupled class B power amplifier is shown in the figure above. g. Design of Class-D Audio Amplifiers -. 256 BJT Amplifiers 6–1 Amplifier OperATiOn The biasing of a transistor is purely a dc operation. Input is sinusoidal. The problem with class-B amplifier design is that we start with an output stage in two halves, each with a non-linear response, which we then combine to try to give a linear response, i. How to build a class d power amp. given that the vast majority of audio power amplifiers use one of these two approaches. Both the class B amplifier and the class A amplifier have the same closed loop voltage gain and are driven by the same input signal. Set the power supply voltage Vcc to 12. Efficiency is the ratio of output power produced for the input power consumed. To solve this problem, amplifiers spend most of their energy ensuring that every part of the signal is replicated faithfully as it is enhancing and transferred to a much higher-power system. . class ab power amplifier ppt Section F4: Power Amplifier Circuits - Class B & AB Recall that the Class B amplifier was also referred to as a push-pull (or complementary symmetry) configuration, where one transistor is used to amplify the positive portion of the input signal and a second to amplify the negative portion of the input signal. 36 from the text book. Thus, when the input voltage amplitude is small, the Class C amplifier cannot be turned on, and only the Class B operation exhibits a linear power amplifier. See this answer23. They still run hot, but nothing compared to a purely Class A amplifier. It simply takes much more dedication, theoretical study and attention to detail than it takes to making a good-sounding class A amplifier. Class B Audio Amplifier Tina Shaw Kendall James Andrew Cruz Criteria Overview Using commonly available operational amplifier to build the DC coupled Class B Audio Power Amplifier Take measurements from both Physical Instruments and Virtual Instruments. Class A power amplifier output stages may use a single power transistor or pairs of the amplifiers output using the turns ratio ( n ) of the transformer and an example of this is given below. Explain why this is. In Class A/B mode, only a few of the LEDs on the front of the XPA-1s lit up, because the speakers ae sensitive. Najmabadi, ECE65, Winter 2012 . Figure 1 shows typical efficiency curves vs. 5 Transformer-Coupled Class B Push–Pull RF Power Amplifier 3. calculations I'm familiar with the efficiency calculation of a class B amp. Maximum power dissipated by both transistors. This lesson discusses basics of class B power amplifier, its conduction cycle & advantages. edu. Draw a circuit for Class C- amplifier and discuss its working? 10. This white paper covers power dissipation calculations for Class B amplifiers. Reading Assignment - RF Power Amplifiers To overcome the problem of linearity A Class -F power amplifier with quarter -wavelength transmission l ine and Here I am referring to class B output power amplifier. Class E. I am attempting to build a compensated class b power amplifier. RF Power Amplifier Design Markus Mayer & Holger Arthaber Department of Electrical Measurements and Circuit Design Vienna University of TechnologyIn class A, it is in the middle of loadline, in class B, on the cusp of cutoff and linear region and in class AB,it is very near to to class B point, but still on the linear portion of loadline. Class D amplifier is the highest power efficient amplifier class in the A, B, AB, and C and D segment. Sign up now. The term 'Class-B' dictates that each amplifying device conducts for exactly 180° of the signal waveform, which implies that they will not conduct at all if there is no signal. The figure-b shows its output characteristics with a centered Q point. As the input voltage V The input to the power amplifier is an almost constant DC voltage between 11 & 12 V and at 15-25 mA. Input power. strong circuit power amplifier(1500Wx2 8 ohms) Features: 1. 7. Linear amplifier (a) (b) (c) (d) Class-A power amplifier Class-B power amplifier . This audio amplifier electronic project will provide a dual 40 watt output power . This a 24 Watt Class A Amplifier circuit made from discrete semiconductors like 2N3055. MARWARI COLLEGE, RANCHI TMH. 20. The Efficiency of Class-C can approach 85 %, which is much better than either the Class-B or the Class-A amplifier. Since the main problem in the design of valve audio amplifiers lies in the difficulty in Imagine we have two power amplifiers, the main amplifier is biased in class B or class AB, and the auxiliary amplifier is biased in class C. A Class AB amplifier can be made from a standard Class B push–pull stage by . Solved problems 1: Single stage BJT amp (CE amp) designing (Dec 97 4 th sem). ADVANTAGES AND DISADVANTAGES OF CLASS A PUSH PULL AMPLIFIER of Class A push pull power amplifier. Reveal Answer26. greatest. Section F4: Power Amplifier Circuits - Class B & AB Recall that the Class B amplifier was also referred to as a push-pull (or complementary symmetry) configuration,Example of a Class -F power amplifier. Class a b 15a 100v power amplifier apex precision product pdf. Power conversion Section F3: Power Amplifier Circuits - Class A Operation As mentioned in the previous section, our studies of BJT and FET amplifiers to date have been of the Class A designation since the output signal is an Class-A amplifiers may be used in output stages of op-amps (although the accuracy of the bias in low cost op-amps such as the 741 may result in class A or class AB or class B performance, varying from device to device or with temperature). The TDA8560 amplifier has an internally fixed voltage gain for excellent channel balance . Write the expression for output power dissipation. how to solve such a problem. 0 V. If I Q Class AB operation improves on Class B linearity. The output of a Class B amp incorporates a positive and negative transistor. By adding the diode, transistors are biased in slightly conducting state even when no signal is present at base terminal, thus removing the crossover distortion problem. = 4 V o−peak V Class B Power Amplifier - Learn Amplifiers in simple and easy steps starting from basic to advanced concepts with examples including Materials Introduction, Transistor Overview, Configurations, Regions of Operation, Load Line Analysis, Operating Point, Transistor as an Amplifier, Transistor Biasing, Methods of Biasing, Bias Compensation, Basic Copyright ©2009 by Pearson Education, Inc. One the design issues with class D is that the power supply modulates the output. This means that the two transistors are biased at the cut off point. 2. 6-2. 7V, VCEsat = 1. of the design problems in class B ampli­ fiers would be solved. 4 ! • power loss. 08. Transistor Q1 and Q2 are the active elements. 3 RF IF Outline (cont. … with non-linearity cancellation by a dual-MOS device that has been recognized in small signal applications such as LNAs [12], and also in large signal applications for power amplifiers as a combination of class A and class B amplifier circuit [16]. Lopresti 2006) updated 05Nov08 KRL Class B Power Analysis - cont. 07. 2014 · Couple of things I noticed. These amplifiers are basically classified into class A, class B, class AB, class C and class D. To replicate the input, each transistor only conducts during half (180°) of the signal waveform Designing a class D amplifier, you start with an enormous handicap because it's trying to do everything but amplify audio. Since the transistor are biased at the cutoff Class B power amplifier provides practically 4 times the power supplied by a single ended amplifier provided load resistance remains the same It gives higher operating efficiency (theoretically 78. Class B Amplifier Power Dissipation Calculations Abstract An amplifier takes DC input power, Pin, and turns it into signal power, Pout, in the speaker. These amps are more complex than the tradition class A/B and filtering problems are simplified. The Power 650 MOSFET is designed to be professionally installed. I use the chip amp to test speakers and when cutting wood so the A/B switcher with fan don't suck up sawdust. Class B Amplifier Circuit Diagram amplifier o and which results in the need of a well regulated power supply. 4 Push–Pull Complementary Class AB, B, and C RF Power Amplifiers 3. At higher output currents, the power transistors conduct, and the STA540 power amplifier. 2018 · In linear audio amplifier classes, liker- Class A, Class B and Class AB, large amount of power is lost due to biasing elements and the linear operation of the output transistors. Total harmonic distortion (Hindi) EFFICIENCY & POWER RATING OF CLASS B POWER AMPLIFIER Presented By:- Shubham Dubey. The circuit requires various switching components like MOSFETs which has low on resistance. The Class B push pull amplifier is almost similar to the Class A push pull amplifier and the only difference is that there is no biasing resistors for a Class B push pull amplifier. Dutta, VIKAS. 5%). 7 V) is: = P L−av P D−av = 1 2 V o−peak 2 R L 2 V o−peak R L V C = 4 V o−peak V CC P DN−av=P DP−av= 1 V o− peak R L V CC Hence: ESE319 Introduction to Microelectronics 13 2008 Kenneth R. 5%. . The class AB amplifier is a variation of a class B amplifier as described above, except that both devices are allowed to conduct at the same time around the crossover point eliminating the crossover distortion problems of the pure class B amplifier. r. Laker (based on P. 2017 · Class AB and Class C Power Amplifiers – Learn Amplifiers in simple and easy steps Therefore, in class AB amplifier design, each of the push-pull transistors is details ofdesigning good power amplifiers (PAs), first with vacuum tubes, and then . Maximum %(. Since the amplifier is a straight-forward class A circuit, the distortion decreases linearly with output voltage. Computer Oriented Numerical Mathematics, N. input voltage is a straight line. The different types of amplifiers are used to amplify the output signals with weak input signals. In contrast, a Class-B amplifier is designed so that only one of the output stages is allowed to be on at a time. the tradition ratings of class A/B amplifiers (20-60%). Then construct the amplifier from the schematic. This lesson discusses power conversion efficiency & power rating of class B power amplifiers. The figure-2 depicts basic class A Power amplifier. circuits using a single power supply to achieve Class AB and Class B operation Here I am referring to class B output power amplifier. Here I am referring to class B output power amplifier. This section discusses transformer - coupled class B amplifiers and class C only. Class B amplifiers are greatly preferred over Class A designs for high-power applications such as audio power amplifiers. RC phase shift oscillator using transistors. Given data: Req gain = 75, . This circuit should be easy to build and understand but I'm having problems with biasing since I don't really know how to bias the bases of Q1 and Q2, so that Q1 would conduct only positive polarity signals and Q2 would conduct only negative polarity signals . Audio Introduction: What are Class D Amplifiers? Class D Amp solved that issue by using a different type of but it is still the biggest problem with Class D Circuit description and power efficiency calculation for the Class A amplifier. Among all the power amplifiers, Class C-amplifier has the maximum efficiency but its use is restricted. Since the transistor are biased at the cutoff Class B Amplifier Power Dissipation Calculations Abstract An amplifier takes DC input power, Pin, and turns it into signal power, Pout, in the speaker. Circuit Power Amplifier has a power output of The figure-4 depicts basic class B power amplifier. 1 INTRODUCTION-DEFINITONS AND AMPLIFIER TYPES Class B operation, with no dc bias power for no input signal, can be shown to provide a maximum of the design problems in class B ampli­ fiers would be solved. Class AB amplifiers all but eliminate the non-linear problems of Class B amps but they ramp up efficiency to Class B levels or more (typically around 50%). This is implemented in Figure 2. Distortion in Amplifier-2 Heat Sink for Power Transistor-1 Heat Sink for Power Transistor-2: Comparison of Amplifier Classes-2 Direct Coupled Class A Power Amplifier Transformer Coupled Class A Power Amplifier Push-Pull Class B Amplifier Complementary Symmetry Class B Amplifier Ch13 class b 1. Benefits of Class B Amplifier. Class B Power Amplifier Check the transistor junctions with the diode test function of the DMM. Class H amplifiers are similar in design to Class AB, but use more stages in the power supply. Answer to For the class B power amplifier of Fig. Alas, Class A is very power inefficient. With the final amplifier we called. The Class B configuration can provide better power output and has higher efficiency(up to 78. 6. e. I understand the common emitter configuration (to boost voltage) and the class b push pull amplifier stage (to boost current). RF Power Amplifier Design Class B and C – Circuit VDD RL G D S f0 ~Stability Problems at high Bandwidths. The great efficiency and simplicity of transistors really shine in this application. Sound is very highly damped but more holographic and neutral to colder sounding in particular than most Class A/B. On the other hand, in class A amplifier using parallel operation of two transistor to get the same output power of 50 watts, assuming maximum conversion efficiency of 50%, dc power requirement is watts. 1)Explain why this circuit introduces crossover distortion (crossover) in the output signal. For most purposes, that’s close enough to what goes on in Class AB amplifiers, the difference being that we’ll remember, to form a non-inverting amplifier from a inverting amplifier. 2 RF IF Outline PA Introduction zPower transfer characteristics zIntrinsic PA metrics zLinear and Non-linear amplifiers zPA Architectures Single-Stage Linear PA zLoad-line theory zTransistors size zInput and Output Matching zSo why is this so hard? High-efficiency PAs zClass A, AB, B and C amplifiers. discussion of a differential amplifier and a basic Class B power amplifier stage The increasing popularity of consumer electronics, primarily in the developing economies is a major factor driving the growth of the power amplifier market. Maximum Pi(dc). It has some good properties in many of the zClass A, AB, B and C amplifiers. It is less used for higher power output stages, as it has poor efficiency. Circuit Power Amplifier has a power output of Operation of class B /AB Power Amplifier using MULTI SIM SOFTWARE Share, Support, Subscribe!!! Subscribe: https://goo. Transistor audio amplifiers have many advantages over their vacuum-tube counterparts, but one circuit that really highlights these advantages is the Class B push-pull power amplifier. As the input voltage V must be well below the carrier power, only Class-A or push-pull Class-AB amplifiers can operate over a band wider than about 1. The trouble is, an opamp can't supply any serious power to a load but, in conjunction with a class B amplifier it can. All design stages showed potential problems at VHF. What I do not like is the "blue-light" around the volume switch. Class B amplifiers are efficient, relatively linear and capable of producing high levels of output power whilst wasting much less of the input power of class A amplifiers. One handy switch on the unit does it. Class A amplifiers have the general property that the output device(s) always the same case as was used for the previous example, with power lines and a load. Notes: Ask your students to specifically identify the change(s) that would have to be made in the following Class B circuit to make it operate as a Class AB amplifier: For a class B amplifier providing a 22-V peak signal to an 8-Ω load and a power supply of V CC = 25 V, determine: . Class B Power Amplifier Lab Manual Cascade amplifier. a. Derive an expression for the efficiency of class B – power amplifiers. The sound signal change C1 and R1 for signal coupling and eradicate noise oscillator go out. Class B Audio Power Amplifier, 15W using NE5532 and transistors. 0 technology, which, instead of the typical and economical switch-mode power supplies of most Class D amplifiers, uses a massive analog toroidal power supply. class A amplifiers (Douglas, 2013). The efficiency is much higher than that of a classA amplifier, and the accuracy of the output is improved. Class D amplifier is the highest power efficient amplifier class in the A, B, AB, and C and D segment. 04. These best-case values for Class A and Class B are the ones often cited in textbooks. The big problem is its sound distortion Class B amplifiers are by far more efficient than class A amplifiers. Class E amplifiers use LC tank circuits, like class C amplifiers, but in a class E amplifier, the active device becomes a switch. This means that just bumping up the supply voltage will NOT make the sound any louder, it will only give you more headroom. For the class B power amplifier of Fig. When feed power supply reach the circuit and feed input signal come in. Solution:- The ac power in class A-operation, P0 is given by the relation,. both class of the exceeding, to honor the Class A was better to the sound quality. class ab power amplifier circuit diagramclass a power amplifier solved problems. Most High Fidelity Amplifiers operate in Class AB. The fundamentals of Class-B push-pull amplifiers have not changed since 1960 when this article appeared in Electronics Word. The transistors for making them have improved in most cases, but the design procedures are basically the same. Upper Saddle River, New Jersey 07458 • All rights reserved. e. (a) Find μ for AM modulation index ma=0. Here is the list of disadvantages of class b amplifier. The Class A amplifier uses devices that always pass high currents, and small signals only modulate these by a modest amount, avoiding the above problems. There will be no cases of cross-over distortion in my circuit,so i think even class B would work properly I tried and got only an amplification of 60 as in schematic. 1) A class A power amplifier operates from a DC source and applied sinusoidal signal. A class D Autor: Engineering Made EasyAufrufe: 1,1KVideolänge: 3 Min. New approach to class B amplifier in which SUb-amplifiers are biased above non-linear region and fed with uni-directional signals produced by the diodes. Using a mains transformer with a secondary winding rated at the common value of 25 + 25V (or 24 + 24V) and 100/120VA power, two amplifiers can be driven at 45W and 69W output power into 8 and 4 Ohms respectively Power amplifier Class-B is the most popular operating modes, and possibly more than 99% of the current series of power amplifier designed and manufactered are of this class. 10. You do not exchange the, the non inverting and inverting terminals in the op-amp, but you change the location of the input voltage and ground to the circuit. Hence, we conclude that class B pushpull amplifier is capable of providing output power 5 times the power dissipation capability of each transistor. 8 speaker load. Amplifier Classes. To replicate the input, each transistor only conducts during half (180°) of the signal waveform DESIGN OF HIGH PERFORMANCE CLASS B PUSH PULL AMPLIFIER PROBLEMS IN CLASS-B PUSH PULL AMPLIFIER 15 This thesis mainly deals with class B power amplifiers. youtube. Where people get it utterly wrong is believing that these problems can't be solved. Substitute for , and for , to calculate . (PNP and NPN) with emitters connected as shown in figure 1. Class D also is more towards tube amp sound in the sense of being more liquid in the midrange in particular. These amplifiers use power devices that are are slightly polarized so that they work in the linear region of the load line for weak signals (Class A) and in Class B for stronger signals. Power amplifier Class-B is the most popular operating modes, and possibly more than 99% of the current series of power amplifier designed and manufactered are of this class. Amplifiers operating in Class AB mode are less power-efficient than Amplifier Classes. Solved Problems on Power amplifier. Solved Problem 20. that Derive an expression for the efficiency of class B – power amplifiers. The Class-A Amplifier Site. Section F4: Power Amplifier Circuits - Class B & AB Recall that the Class B amplifier was also referred to as a push-pull (or complementary symmetry) configuration,Linearity of the Class-C amplifier is the poorest of the classes of amplifiers. in order to minimize static power consumption and increase amp's input The Class AB amplifier circuit is the combination of both Class A and Class B amplifier. DO NOT USE THIS TAG FOR POWER SUPPLY PURCHASING QUESTIONS, simulation Class B audio amplifier OrCAD PROBLEM 3: An amplifier uses two DC supply rails, V+ and V Class B Audio Amplifier Tina Shaw Kendall James Andrew Cruz Criteria Overview Using commonly available operational amplifier to build the DC coupled Class B Audio Power Amplifier Take measurements from both Physical Instruments and Virtual Instruments. CLASS-B PUSH PULL AMPLIFIER Switch on the power supply and signal The class AB amplifier is a variation of a class B amplifier as described above, except that both devices are allowed to conduct at the same time around the crossover point eliminating the crossover distortion problems of the pure class B amplifier. Problems for Amplifier Section Lecture notes: Sec. amplifier classification class b amplifier operation transformer-coupled push-pull stages tuned power amplifiers power dissipation considerations. Figure 5. A single LED or two was as often as much activity as I got with some music. L. ) Real-World Design Example zSelecting discussion of a differential amplifier and a basic Class B power amplifier stage, both of which represent common building blocks of the operational amplifier. Solved in a swamped amplifier the effects of r e becomewhere Psig is the power carried by the sidebands and Pt is the total power of the AM signal. Class C. This page was last updated on 20 July 2001 . Since the active device is switched off for half the input cycle, the active device dissipatesNew Approach to Class B Amplifier Design by Peter Blomley* The class B amplifier has established itself as the most versatile and lowest cost ampli­ fier known. o The circuit diagram of a Class B push pull amplifier is shown in the diagram below. phpList advantages and disadvantages of class B amplifiers. In this section we look at the design of a 1 Watt FET power amplifier using the 2N7000 n-channel enhancement mode MOSFET. , calculate:a. We will cover four possibilities with class A, C, E designs and a suggestion for a class B design. Design of class B power amplifier (June 97). Low-level signals are dealt with in the same Actually, the output stage switches in a class D amplifier, although the power supply may also utilize class-D circuitry. JLH Class A Amplifier (1969) high-quality audio power amplifiers. They are sometimes used as medium-power, low-efficiency, and high-cost audio power amplifiers. While the use of biasing resistors may not solve the temperature problem, one Class B power amplifier consists of two complementary pair of power transistors. 5% for the Class B amplifier, and 90% for the Class D amplifier (see Figure 5). For a class B amplifier, collector current flows for: For Q1 in the amplifier shown in the figure, solve for There is another way to look into this problem: If we consider the amplifier as an is in power radio-frequency amplifiers. Assuming relatively ideal transistors, what is the output voltage for maximum power-conversion efficiency? Transistor audio amplifiers have many advantages over their vacuum-tube counterparts, but one circuit that really highlights these advantages is the Class B push-pull power amplifier. chun-hsien su 中央大學電機系 蘇純賢 chunsu@ee. 8. 3 Amplifier Efficiency The power efficiency of an amplifier, defined as the ratio of power output to power input, improves (gets higher) going from class A to class D. The circuit is similar in design to my ' Basket Case ' amplifier but without the preamp and tone controls . In the class B amplifier, there is no DC base bias current as its quiescent current is zero, so that the dc power is small and therefore its efficiency is much higher than that of the class A amplifier. This Leipasi Electronics Co. POWER AMPLIFIERS 15. Also, the input power is not completely utilized. Numerical Methods, (Idea of objects, class, data abstraction iv ABSTRACT Class-F Power Amplifier with Maximized PAE By Kai Shing Tsang Background Due to the rapid development of telecommunication devices, operating speeds are gettingExample Amplifier Design Design a single stage amplifier with G = 14 dB and input match. In this way, for small output currents, the output transistors are turned off, and the op-amp provides all of the output current. Give reasons. efficiency of transformer coupled class A power amplifier is maximum of 50% No Problem! Incredible Steal of Snooker Chapter 6 BJT Amplifiers Amplifier Operations [5], [7] 6. amplifiers, and despite the fact that the measured performance cannot compete with modern amplifiers, they sound very good and they do not expose you to the same degree of listening fatigue as many solid state amplifiers, truly or falsely!, are accused of. ) The analysis of Audeze Deckard Headphone Amplifier and DAC Class A is found most often in applications that require low power and low distortion, such as for radio or guitar amplifiers. The class AB amplifier is a variation of a class B amplifier as described above, except that both devices are allowed to conduct at the same time around the waveforms crossover point eliminating the crossover distortion problems of the previous class B amplifier. gl/LfhLB2 Youtube: http://www. Push Pull Amplifier Circuit Diagram - Class A, …Diese Seite übersetzenhttps://circuitdigest. An old school Class A/B with linear power supply, a Class A/B with switching power supply and a Class D chip amp. Najmabadi, ECE65, Winter 2012Crossover distortion is more of a problem in low and medium power class B amplifiers and the method used to eliminate it, is to use a class B amplifier that has some bias (and quiescent current) added so that the output transistors are conducting continually, and so avoiding the ‘dead zone’ of class B. tw. 14. In in fact there kirakira VBE voltage clamp of 0. Here I have enlisted few of the benefits of class b amplifier. (b) Show that for a single-tone AM, μmax is 33. 2V and RL = 8Ω. Class H. d. 12. Class B Amplifier Operation Class B The amplifier conducts through 180 of the input. pdf · PDF DateiCollection of Solved Feedback Ampli fier Problems This document contains a collection of solved feedback amplifier problems involving one or more active devices. Figure 2: Push-pull Class-B amplifier. , Ltd. transformerless class ab power amplifier. gl/LfhLB2 Youtube: http://www. class b power amplifier solved problems Today all linear amplifiers used by hams belong to Class AB which efficiency does not exceed 50%, there are tubes or solid-state amplifiers. The most common (a) Refer to Figure 12. The solutions make use of a graphical tool for solving simultaneous equations that is called the Mason Flow Graph (also called the Signal Flow Graph). This was solved by the design of The circuit of Figure corresponds to a class B amplifier, where Q1 and Q2 have VBE = 0. main features of a large-signal amplifier are the circuit's power efficiency, the maximum amount of Class AB: An amplifier may be biased at a dc level above the zero base current level of a signal that varies over the full cycle (using sample-and-hold circuitry) to Circuits and examples are provided later in this chapter. Hello, I am working on a lab for school and I am having a problem. View More Presentations Power of natureClass-A Amplifier: Power Distribution The figure-a shows that the connection of common-emitter transistor which forms the active element of a single stage class-A amplifier . Class-B Feedforward Amplifier. Amplifiers operating in Class AB mode are less power-efficient than pure Class B operation. and how to get those 78,5% but how do you calculate in the Abstract—A novel high-voltage analog power amplifier derived from a well-known complementary class B amplifier is presented in this paper. However, the price paid for the improvement in the efficiency is in the linearity of the switching device. It has smaller heat dissipation, so small heatsink is needed. Class-B amplifier is also favoured in battery- operated devices, such as transistor radio. Class AB arrangements are probably the most commonly employed system for power amplifier output sections, although ‘Pure’ Class A is often used for low current/voltage applications where the poor power efficiency isn’t a problem. class ab amplifier advantages and disadvantages. The solution is to find a ‘half-way house’ that tries to take the good points of each and minimise the problems. 9. An Analysis of Class B and Class C Amplifiers For the case of the class B amplifier , the voltage Eo is equal to zero, and only the first term of the numerator and the first two terms of the denominator This little amp solved the problem; volume on the unit is easily adjustable and you can turn off the audio feed completely. Set the AC input voltage from the function generator to a peak-to-peak The power conversion efficiency of the class B amplifier (accurate for |V o-peak | > 0. The Class AB amplifier circuit is the combination of both Class A and Class B amplifier. so that a graph of output voltage vs. Highly efficient as compared to class A amplifiers; NO DC component in its output at all; Disadvantages of Class B Amplifier. Problems. ece. Class B power amplifier But that does not mean the problem is over, because the transistor have to-not-an ideal. Class A power amplifier. in class B but the way they are . High Voltage, High Efficiency MOSFET RF Amplifiers – The most common problem associated with determined by the class of operation, the output power Class AB power amp. A Class A audio amp is typically associated with high linearity but low efficiency. This is mainly due to the excellent work in the field of semiconduc­ tor circuit design by H. In fact, the example shown in Figure 2·1 is particularly inefficient as it is Single Ended . Class C Power Amplifier Lab Manual This project will introduce two common power amplifier topologies, and also This lab introduces two amplifier topologies: the Class-B amplifier, and the (c) A frequency sweep of the amplifier (the plot of class B will look different) from 10. You Push, I'll Pull . Class Distinction in Audio Amplifiers . Tobey and J. The theoretical maximum efficiency of Class-D designs is 100%, and over 90% is attainable in practice. The efficiency of class-A PA is improved by placing output transformer instead of resistor as its load. The input power is 305mV for 24W output into 8 Ohm (33dB gain) and the THD is very low. by J. Class B amplifiers use a push-pull amplifier topology. The amplifier incorporates internal battery line filtering and exten-sive noise prevention circuitry. Class G power amps solve this supply voltage problem by using a charge pump to boost Class A is more towards a warmer tube amp sound than A/B. Regional Power Amp, self-control it effect on several well-notorious in the function of group of students A, Class B, Class AB and so forth. Though the efficiency of class B power amplifier is higher than class A, as only one half cycle of the input is used, the distortion is high. RF Amp Devices As for proper operation of this amplifier a Class B output stage op-amp is required, the original circuit was modified accordingly. Transformer coupled Class B amplifier. Sign up now to enroll in courses, follow best educators, interact with the community and track your progress. Class AB amplifiers are the most common type of amps for home theater and even car stereos. Power efficiency of Class A, Class B, and Class D output stages. In push-pull outout configuration, two identical but anti-phase signals from phase splitter are provided to bases of pair of transistors. The purpose of biasing is to es-tablish a Q-point about which variations in …remember, to form a non-inverting amplifier from a inverting amplifier. Collection of Solved Feedback Ampli fier Problemsusers. ncu. 6 Class AB, B, and C RF Power Amplifiers with Variable-Envelope Signals Class B amplifier efficiency approximately by 75%. Class B is far more efficient, but can lead to signal distortions. In this article it is hoped to complement the work of Solutions for Chapter 12 Problem 16P. The different types of amplifiers are used to amplify the output signals with weak input signals. Schematic diagrams of a class b power amplifier b prelinearized. This circuit should be easy to build and understand but I'm having problems with biasing since I don't really know how to bias the bases of Q1 and Q2, so that Q1 would conduct only positive polarity signals and Q2 would conduct only negative polarity signals. How to solve Electronic Devices Power Amplifiers problems? You can easily solve all kind of Electronic Devices questions based on Power Amplifiers by practicing the objective type exercises given below, also get shortcut methods to solve Electronic Devices Power Amplifiers problems. Amplifiers operating in Class AB mode are less power-efficient than pure Class B operation. (a) Refer to Figure 12. , calculate:a. Theoretically, a switching amplifier (which dissipates virtually no power as heat) has an efficiency of 100%, while Class B amps have a theoretical maximum efficiency of 78% and Class A amps 20–50%. Another version of the Class-A amp looks exactly the same as a standard Class-AB (Class-B) power amp, except the quiescent current is increased to just over 1/2 of the peak speaker current. output power and total harmonic distortion is shown in Fig. As this method has some properties of both class A and class B it is called Class AB. C. c. Notes: Ask your students to specifically identify the change(s) that would have to be made in the following Class B circuit to make it operate as a Class AB amplifier: 2. Overcoming this lack of fidelity requires the use of multiple transistors which employ Autor: The Offset VoltAufrufe: 41KModule 6 Unit 6 Power Amplifiers - NPTELnptel. 36, calculate: a. Output power. in/courses/115102014/downloads/module6. A simplified Class B amplifier Though the efficiency of class B power amplifier is higher than class A, as only one half cycle of the input is used, the distortion is high. ItClass A amplifiers vary the large Quiescent Current in order to generate a varying current in the load, hence they are always inefficient in power terms. Note that this efficiency is high from very moderate power levels up to clipping, whereas the 78% maximum in Class-B is obtained at the onset of clipping. class b amplifier. Output only conducts for 180 or one-half of the AC input signal. 5%), because the amplifying element is switched off every half the time period and so cannot dissipate power (Gupta, 2012). As for Class bD amplifiers they have an efficiency rating closer to that of class D amplifier (75-80%) vs. A simplified Class B amplifier Class B amplifier efficiency approximately by 75%. This problem has been solved: Chapter: Chapter 12, Problem 16P is solved. Collector current waveforms for transistors operating in (a) class A, (b) class B, (c) class AB, and (d) class C amplifier stages. For most purposes, that’s close Transistors as amplifiers and switches . 1. edu/mleach/ece3050/notes/feedback/FBExamples. B sig o o Amplifier Parameters This is a common collector amplifier How to solve Electronic Devices Power Amplifiers problems? You can easily solve all kind of Electronic Devices questions based on Power Amplifiers by practicing the objective type exercises given below, also get shortcut methods to solve Electronic Devices Power Amplifiers problems. 0. Class B Power Amplifier 2. 2 Contents Chapter 1 Getting Familiar with Class D Audio Amplifier Chapter 2 Latest Class D Audio Amplifier Technology Trend Chapter 3 Identifying Problems ~ Performance Measurement of Class D AmplifierQuestions & Answers on Power Amplifier The section contains questions and answers on power amplifiers, amplifiers distortion, heat sink for power transistors, direct and transformer coupled class amplifier, push pull and symmetry class amplifier. Sound is still more damped however. In reality, there are very, very few 'true' Class-B amplifiers. The same problem was treated by Douglas A class B amplifier drove the ground of a floating low voltage power supply for the power output stage of class A amplifier. class b power amplifier solved problemsPower amplifier classes are, in electronics, letter symbols applied to different power amplifier A class A amplifier is conducting through all the period of the signal; Class B only for one-half the input being 'off' is not at 'zero signal', so the problems of crossover distortion associated with class-AB and -B designs is avoided. In Class A amplifier, If the collector current flows all times during the full cycle of the input signal, the power amplifier is known as class A power amplifier. Problem 15ST: The power dissipation of a class C amplifier is normally(a) 2238 step-by-step solutions; Solved by professors & experts GATE 1994 ECE Class A Transformer coupled power amplifier GATE paper. Here we will discuss regarding the technical specifications of the first type of amplifier i. Power amplifiers are categorized into different types such as an Audio power amplifier,an RF power amplifier, vacuum tube power amplifiers, transistor, FM power amplifier, stereo power amplifier and a class-A, class-B, class-C, class-D & class AB power amplifiers. The above two Drawbacks can be easily solved by using CLASS C POWER AMPLIFIER WORKING AND CIRCUIT Every innovations starts from a simple day to day life Answer to Power Amplifiers & Emitter Followers 1. Both of the Class D amps have feedback networks in them and a high Power Supply Rejection Ratio (PSRR). Figure 2 shows an alternative strategy, in the form of a push-pull amplifier output stage. com/lesson/class-b-power-amplifier-hindi/HOQ0EBUSThis lesson discusses basics of class B power amplifier, its conduction cycle & advantages. To improve the full power efficiency of the previous Class A amplifier by reducing the wasted power in the form of heat, it is possible to design the power amplifier circuit with two transistors in its output stage producing what is commonly termed as a Class B Amplifier also known as a push-pull amplifier configuration. Class B power amplifier (Hindi) | (Hindi) Power …Diese Seite übersetzenhttps://unacademy. This audio amplifier can drive up to 24W Class A into 8 Ohm speaker with an audio bandwidth of 100mHz to 100kHz flat. see next paragraph). Bowes2, R. Figure 1. What reasons will you assign for higher conversion efficiency of Class B-amplifier as compared to Class A –amplifier? 9. 5 Nov 2008 Class B Audio Amplifier Example. Class B power amplifier provides practically 4 times the power supplied by a single ended amplifier provided load resistance remains the same It gives higher operating efficiency (theoretically 78. Early transistor power amplifiers had their share of problems: crossover distortion, poorly designed output stages, slew rate limitations, transient slewing, little attention paid to power supplies. In order to compensate these problems, the push-pull configuration is introduced in class B amplifier. org/Amplifiers/amplifiers53. Class A wastes lots of power, B the least, but requires two amplifiers , AB slightly more power than B but avoids distortion near the zero crosspoint. Electrical Engineering Class B amplifier problem? A class B output stage operates from ±5-V supplies. As an example, if the amplifier’s power output is reduced to 10% of its maximum power capability, a Class D amplifier’s efficiency will drop to about 78%, but a Class B amplifier will drop to 28% and a Class A amplifier will drop to 3%. R. Avoid the LM741 or LM1458 for this reason. B sig o o Amplifier Parameters This is a common collector amplifier Crossover distortion is more of a problem in low and medium power class B amplifiers and the method used to eliminate it, is to use a class B amplifier that has some bias (and quiescent current) added so that the output transistors are conducting continually, and so avoiding the ‘dead zone’ of class B. This type of power amplifier configuration is generally called a Class B Can you ki ndly assisst on best way of solving this problem. Class B Amplifiers. If possible, try to obtain TIP41 and TIP42 transistors, which are closely matched NPN and PNP power transistors with dissipation ratings of 65 wattsCollection of Solved Feedback Ampli fier Problems This document contains a collection of solved feedback amplifier problems involving one or more active devices. com/electronic-circuits/push-pull-amplifierThe Class AB amplifier circuit is the combination of both Class A and Class B amplifier. This circuit should be easy to build and understand but I'm having problems with biasing since I don't really know how to bias the bases of Q1 Section F4: Power Amplifier Circuits - Class B & AB Recall that the Class B amplifier was also referred to as a push-pull (or complementary symmetry) configuration, where one transistor is used to amplify the positive portion of the input signal and a second to amplify the negative portion of the input signal. SX series power amplifier use excellent components,high efficiency,high speed ,high power output circuit 2. Another benefit of using Class E is that the amplifier is “de-signable Normalized Output Power It’s easy to show that for Class A/B/C amplifiers, the efficiency and output power are given by: It’s useful to normalize the output power versus the product of V bk and I max (I dc) Class A power amplifier is the one of simplest type of amplification system uses transistor in CE configuration . The big problem is its sound distortion The Class A amplifier uses devices that always pass high currents, and small signals only modulate these by a modest amount, avoiding the above problems. (Assume V BE = 0) 1 +20V 1k k B v i 50Ω k 100Ω 50Ω v oProblems for Amplifier Section Lecture notes: Sec. The circuit of Figure corresponds to a class B amplifier, where Q1 and Q2 have VBE = 0. Power amplifier Class-B is the most popular operating modes, and possibly more than of the current series of power amplifier designed and manufactered are of this class. This audio amplifier IC is specially designed for car audio applications. Previous years problems part-2 (Hindi) 11:17. This action is achieved by pre-biasing the two transistors in the amplifiers output stage. As time goes by you will see more amplifier classes appear that offer improvements over the general class A/B and class D designs. 1 A class-A series fed amplifier has VCE(max) = 25 V, To improve the full power efficiency of the previous Class A amplifier by reducing the wasted power in the form of heat, it is possible to design the power amplifier circuit with two transistors in its output stage producing what is commonly termed as a Class B Amplifier also known as a push-pull amplifier configuration. Power amplifiers vtu e. google. Lin', R. class ab amplifier vs class d. As for Class bD amplifiers they have an efficiency rating closer to that of class D amplifier (75-80%) vs. However, the overlap eliminates the crossover distortion associated with Class B amplifiers. The STA540 contains four single-ended, class-AB audio amplifiers assembled in a Multiwatt15 package. Class-B. Designing a BJT Amplifier given some constraints. It is required to design a Class B output stage to deliver an average power of 20 W to an. Maximu 738 step-by-step solutions; Solved by professors & experts; iOS, Android, & web As we said above, the Class AB Amplifier is a combination of Classes A and B in that for small power outputs the amplifier operates as a class A amplifier but changes to a class B amplifier for larger current outputs. The operating May 23, 2017 Sample power calculations for a class B push-pull output stage. It consists of a power transistor to drive the load and a darlington pair to drive the base current of power transistor w. A discussion of design problems and how to overcome them . In the figure, it is noticed that the output voltage waveform is a square wave while the drain current is a half -rectified sinusoid. Defining the Class-B is the amount of bias voltage that causes conduction of both output devices to overlap with the current and thus produce the minimum amount possible Class B Audio Power Amplifier, 15W using NE5532 and transistors. The Class AB amplifier circuit is the combination of both Class A and Class B amplifier. (This would not necessarily be the case in a class B system if any significant amount of cross-over distortion was present. But that does not mean the problem is over, because the transistor have to-not-an ideal. It is difficult to realize at first that a class B amplifier has to have this non-linear region in the sub-amplifier characteristic so that the two halves of the waveform can KEY Bias voltage(V) 1 0 2 0-2 3 0-4 4 0-6 5 0-8 6 1-0 7 1-2 8 1-4 9 1-6 10 1-8 11 2-0 --+i i+-- The fundamental difference between Class B and Class AB operation is biasing: both transistors are “on” for a brief moment in time around the zero-crossover point in a Class AB circuit, where only one transistor is supposed to be on at any given time in a Class B circuit. Here each transistor feeds current to load for half cycle only. Theoretically, power mains-related hum problems due to ground loops will be minimized if the cable shield doesn’t connect to both the device under test (DUT) and the test equipment. Title: Slide 1 Author: David L. Maximum Efficiency for Class B Power Amplifier Amplifier By Sasmita March 3, 2017 We have already seen in our previous article about class B power amplifier that a push-pull circuit uses two transistors working in class B operation . Transformer coupling is solution for this problem and such amplifiers are called transformer coupled Class B amplifiers. HE BIPOLAR JUNCTION TRANSISTOR. A complete Class-B power amplifier Chapter 7 Compensation, slew-rate, and stability Compensation in general Dominant-pole compensation Lag compensation Including the output-stage: inclusive Miller compensation Nested feedback loops Two-pole compensation Output networks Amplifier output impedance Minimising amplifier output impedance Zobel networks Output inductors The output …Class AB amplifiers all but eliminate the non-linear problems of Class B amps but they ramp up efficiency to Class B levels or more (typically around 50%). Class B Power Amplifiers - Learn About Electronics www. If we consider the example of Public address systems where, Power amplifiers are classified as CLASS A, CLASS B, CLASS AB, CLASS C . Q1 and Q2 in the Power Amplifier should be mounted on the same finned heatsink, of about 80x40x25mm. Section F3: Power Amplifier Circuits - Class A Operation As mentioned in the previous section, our studies of BJT and FET amplifiers to date have been of the Class A designation since the output signal is an There’s Class A, Class AB, Class B (and a few others). Do not connect the load resistor R. 8:1 with only one fixed-tuned harmonic-suppression fil-ter. V. The class B amplifier is used in push pull arrangement in which one amplifier operates in positive half cycle and other amplifier operates in negative half cycle. The problem with amplifiers is that as efficiency improves, faithfulness to the original signal diminishes. Heiserman Created Date Be sure to use an op-amp that has a high slew rate. It is the most commonly used audio-power amplifier. comThis is the electronic devices questions and answers section on "Power Amplifiers" with explanation for various interview, competitive examination and entrance test. BaxandalP. ) Harmonic output of Class-E amplifiers is similar to that of Class-B amplifiers. Here’s a bit of history and an explanation. It is difficult to realize at first that a class B amplifier has to have this non-linear region in the sub-amplifier characteristic so that the two halves of the waveform can KEY Bias voltage(V) 1 0 2 0-2 3 0-4 4 0-6 5 0-8 6 1-0 7 1-2 8 1-4 9 1-6 10 1-8 11 2-0 --+i i+-- Solutions for Chapter 12 Problem 16P. The operating The main features of a large-signal amplifier are the circuit's power efficiency, the maximum amount Class AB: An amplifier may be biased at a dc level above the zero-base-current level of class B and Check EXAMPLE 12. The main problem with class B push pull output stages is that each transistor conducts for NOT Solved problems 1: Single stage BJT amp (CE amp) designing (Dec 97 4 th sem). load shorts, system power problems, and internal failures. A very simple class B power amplifier can be designed using TDA8560 audio IC. Author: Ariel Created Date: 3/29/2007 3:35:41 PMThe figure-2 depicts basic class A Power amplifier. ac. Since input must be matched, let’s select the load for gain/stability. 7 volts which causes transistor is in OFF state although the flow has a larger Ib some mA from 0. That means the conduction angle is 180° for a Class B amplifier. The Q-point is set at the cutoff point. learnabout-electronics. Power amplifiers are categorized into different types such as an Audio power amplifier,an RF power amplifier, vacuum tube power amplifiers, transistor, FM power amplifier, stereo power amplifier and a class-A, class-B, class-C, class-D & class AB power amplifiers. In previous designs the transfer from rail to rail has caused output glitches; this problem is solved in the Douglas Self Class-G power amplifier by some innovative and authoritative design, including the use of Schottky diodes to eliminate carrier-storage glitching. This is thought by some that this is not a 'real' Class-A amplifier. t given signal. Previous Years Problems: Part-1 (in Hindi) 9:35. Solved examples with detailed answer description, explanation are given and it would be easy to understand. 80 watt fm stereo transmitter. Class-B Push-Pull Source Follower Output Stage + Vi VDD VSS (3) (4) (1) (2) RL Vo M1 M2 Figure 2. Experiment 6: The bipolar junction transistorThe Class A amplifier uses devices that always pass high currents, and small signals only modulate these by a modest amount, avoiding the above problems. youtube. The Class AB amplifier is a blend of Class A and Class B, and strives to offer a compromise in efficiency and performance. By class, class D power amplifier is expected to overtake class A and class B power amplifiers during the forecast period. MBL claims to have solved these myriad problems with its LASA (Linear Analog Switching Amplifier) 2. These goals were achieved by using a discrete-components op-amp driving a BJT complementary common-emitter output stage into Class B operation. Circuit efficiency. 30. Bailey· and P. Class B Audio Amplifier Most audio “power” amplifiers use a class B configuration, exacerbating the problem of forward voltage drop change. This is similar to Class B but a tuned circuit brings only the intended frequency out of the device