Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [class-ab]

This tag can be used to denote questions related to analogue amplifiers working in AB-mode.

Class AB amplifiers combine some properties of class A and B amplifiers. While class A amplifiers operate within a 'linear' part of the characteristic of a BJT yielding a high linearity but low efficiency class B amplifiers operates over the full U-I characteristic of two BJT with higher efficiency but poor linearity.

For building class AB amplifiers parts of the characteristic of two BJTs is 'cut away' by adding bias diodes. The more linear rests of both characteristics is 'glued' together to produce a compromise of efficiency and linearity.

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Class AB crossover distortion diode fix

In the class AB amplifier shown below, we use diodes to make the PNP and NPN conduct equally. How do the diodes make them conduct equally? Is there some intuition I could use to understand this phenomenon?
lub2354
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Class AB power amplifier from "Electronic Devices" by Thomas L. Floyd

I am an electronics engineer. I work as an industrial automation engineer in industry. As an electronics engineer, I love amplifiers and other stuff. I was reading Electronic Devices by Thomas L. Floyd (great engineer) and I came across this…
Waqas Ahmad
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How to bias a MOSFET class AB amp?

I'm working on a class AB amplifier that is used to either source or sink current. The reason for using MOSFETs is space constaints and that high power BJTs are only available in large leaded packages. I tried to look around for some biasing…
Lars Hankeln
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Is this supposed to be the output of this circuit?

I used LTspice to simulate a oscillator circuit to convert DC to AC. The oscillator is then connected to a class AB power amplifier to increase the circuit current. The load of the Class AB amplifier is two coupled inductors to simulate wireless…
Jeremy
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Biasing a DIY current feedback opamp

For a personal project, I'd like to make a discrete current feedback opamp. Here's a simplified schematic: The question is about how to bias Q3/Q4. For a nice class-AB output, the sum of both Vbe's should be constant. In a common collector output…
bobflux
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Why only common collector method is used in class AB amplifiers?

I have recently started to study about class AB amplifiers online, as a newbie, i have found every schematic of the class AB amplifier is in common collector circuit just like this Schematic i find everywhere in internet... simulate this circuit –…
Subha Jeet Sikdar
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How is the quiescent current and emmiter resistor determined on the driver and pre-drivers of a class-AB audio amplifier output stage

I am reading online about discrete audio amplifiers. I have learned about the input differential pair, the voltage amplifier stage, and now I'm learning about the output stage. I have learned that you want to bias the output to have about 25mV to…
johnny24
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Class AB amplifier sizing

I have simulated a class AB amplifier as shown in the attached diagram. Its working pretty fine at 5kHz and 500mV input signal. However, the simulation fails when I try to change the requirements to fit the specifications of my project which…
Farai Mahachi
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Resistors values for class AB amplifier

I'm designing a class AB amplifier with a vbe multiplier to amplify the output current. I try to choose the resistors values by doing a DC analysis but when I simulate the circuit in AC, the output current is much smaller than the input. I think my…
Lokath
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How to increase CE amplifier gain to 12?

The gain needs to be increased to 12, currently it is at 10 but I cannot seem to increase this any more. The circuit topology cannot change, but the component values can - except R4, the 56 kΩ resistor. The input signal is 1 Vpk at 1 kHz. Therefore,…
Tom
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What do these components of an AB amplifier do?

I'm trying to learn about class AB amplifiers by reverse-engineering a few I see here on SE. I borrowed this schematic from this question as a starting place. Ignoring the fact that the circuit lacks emitter degeneration at the output -- which I…
nuggethead
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Troubleshooting class AB amp with only multimeter

I made a stereo amplifier on a PCB which is two of the following circuit. One channel amplifies the audio decently, but the other channel has NO sound regardless of how loud I make the input. My sound source for testing is the earphone jack of my…
mike_s
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How ca I match a class AB amplifier to voltage multiplier through a transformer?

So here it goes, I will keep this issue as simple as possible. I have this Class AB amplifier over here, that brings me a 60 Hz sinusoidal signal up to aprox 15Vp. Must be said that the sinusoidal wave is being generated by PWM and a MFB 2nd order…
García Morales Kevin
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A/B power amplifier: difficulty getting a full output voltage swing

I have been designing an A/B voltage amplifier using the TIP31C/32C power transistors (schematic shown below.) I have a significant loss in voltage gain which I haven't able to negate. Is this inherent to a class A/B output stage or is the gain of…
Samuel Newport
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Voltage follower configuration

for the LM4952 chip (class AB amplifier), I wanted to add an NE5532 OA in voltage follower configuration at its input. That to take care of whatever input source will be plugged into it. Is it a good idea or just a waste of money?
Status Re
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