Questions tagged [class-ab]
This tag can be used to denote questions related to analogue amplifiers working in AB-mode.
22
questions
0
votes
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
votes
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 ...
0
votes
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 ...
0
votes
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.
...
0
votes
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....
0
votes
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
votes
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
votes
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 ...
0
votes
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
votes
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 ...
1
vote
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 ...
3
votes
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
votes
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
vote
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
vote
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
vote
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 ...
1
vote
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 ...
0
votes
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.
1
vote
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
vote
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....
0
votes
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
vote
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 ...
