Questions tagged [class-ab]

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

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1answer
58 views

BJTs dangerously getting hotter as drawn current accumulating

I already ask a few questions on this project (so i won't explain everything again as it would be too long). I basically have a high power opamp (OPA462) to which i feed a signal (but i offset it ...
2
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3answers
201 views

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 ...
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1answer
57 views

How should I size the transistors in the class AB linear amplifier

If I want to design a class AB linear amplifier as the following one, how should I determine the width of the pmos and nmos? Class AB amplifier specifications: Vdd: 6V Input: 0.5V to 5.5V Output ...
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0answers
61 views

Class AB linear amplifier design

I am trying to design a class AB linear amplifier. The required peak current is 450mA. I am just using an ideal biasing at this stage. The schematic is as follows: Here are the resulting waveforms. ...
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0answers
46 views

Class AB amplifier using push-pull pair signal decay

I'm trying to build a class AB amplifier with push-pull pair of power transistors for audio amplifier. the circuit works fine with low voltage(~0.2V) but the input peak voltage varies between 0.2 - 2V....
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1answer
61 views

Adjustable power supply from +5V to -5V

Depending on the orientation of a nulling coil I need an adjustable voltage supply from ~+5V to -5V upto ~200mA. I've tried a few circuits similar to Class AB amplifiers such as the one shown below, ...
0
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1answer
108 views

Class AB Amplifier - Weird oscilloscope output

I have built this little kit for a class AB Amplifier. This is the schematic if you do not want to follow the link It works fine, I can hear decent sound. I then tried to check the output with an ...
0
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1answer
70 views

Calculating output impedance without measuring open-loop output voltage of a push-pull Class AB MOSFET Amplifier

So I am building and analyzing a Class AB / push-pull amplifier implemented with MOSFET as depicted in the following schematic: R2 is the load. The input is an AC signal with 3V amplitude and 1KHz ...
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1answer
84 views

Complementary pair - Role of capacitor on emitter

I bought this little kit for a class AB amplifier. The second stage is quite clear (and typical), but I am struggling to understand the role of capacitor C2 on the emitter branch in the first stage. ...
2
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4answers
2k views

Design a class AB audio amplifier

I am required to design a class AB audio amplifier to deliver 10W to an 8Ω speaker as shown, but I don't know where to start. The bandwidth is to cover the range from 20Hz to 18kHz. Input voltage is ...
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2answers
70 views

What is the role of the Op-Amp integrator in this circuit?

Helo dier community! I got a 400 Hz broken Power Inverter and reverse-engineered the circuit just for the simplicity of repairing it. Then I got deeper in and started to understand the engineering ...
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3answers
279 views

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 ...
3
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1answer
85 views

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 ...
1
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1answer
128 views

Cross coupled Class AB output stage

A simple question about ClassAB common source amplifier. There are two circuits which I have attached with this question, the one on the left is a standard cross coupled circuit which I have taken ...
1
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1answer
117 views

How do analyze input impedance of Class AB amplifier biased with resistors?

EDIT: I realize that the original circuit is deeply flawed and will burn up upon re-entry. Thanks to anyone who can help me understand why! I'm learning to analyze Class AB amplifiers, but haven't ...
1
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1answer
42 views

What equation do I use for simple class AB input impedence?

I'm a novice at this. I've done some figuring and would love to know if I've got this correct before I move to more complicated circuits. I have the simplest Class AB amplifier and I'd like to know ...
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3answers
113 views

Amplifier power problems, power supply limitations, or end stage base current draw

So I am experimenting with various signal generating, op-amp and power amplifier circuits. And I have limited access to technology. Where I am at, everything you buy is twice the price because of ...
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3answers
106 views

How can I overcome the distortion using in this circuit by using same products as we see in picture ? Or we can use 2n700 series, 3906 and 3904 bjts

Or we can use 2n700 series, 3906 and 3904 bjts. My aim is 10W, gain 100-1000 (adjustable), 50hz-20khz amplifier by using this basic components.
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2answers
74 views

How can I calculate low and high frequency in my circuit?

How can I calculate low and high frequency in my circuit? I have used an 8-ohm speaker.
1
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1answer
405 views

LTSpice produces incorrect simulation for Class AB amplifier

I have been building a Class AB amplifier simulation using LTSpice. While it simulates well for transient analysis (voltage gain of 0.9 at peak), using ac analysis the the voltage gain drops to 0.268....
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1answer
292 views

Class AB Amplifier - Q point

In a class AB amplifier, why is the Q point much closer to the cutoff voltage as compared to a Class A amplifier which is at the center. Wouldn't this clip the AC signal if its too close to Vce. ...
1
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2answers
105 views

Two-stages class AB amplifier

I'm studying the following two-stages class AB amplifier: Basically it is a standard two-stages op-amp (i.e. the cascade of a differential pair with active current mirror followed by an inverter with ...