I am looking ake a headphone amplifier. Since op amps has limited current capacity I was wondering about output buffer. I wanted to use diamond buffer. I simulated a few output buffers and diamond buffer performed the worst.😡
I have been searching internet but could not find any article on how design diamond buffer, how to select bias current and driver emitter degeneration resistor. 😕
According Ltspice simulation a simple Push Pull is working better than Diamond buffer and paralleling op amp as unity gain buffer out performs all of them.
Simple push pull performs better with increasing the bias current but Diamond buffer suffers.
For similar bias current Diamond buffer worse than Simple Push Pull Circuit.
Tweaking current and driver emitter degeneration register does improve thd a little bit. But I am clueless as how to properly select bias and degeneration register for any given component.
Any assistance would be greatly appreciated.
simulation file included.
I have been searching internet but could not find any article on how design diamond buffer, how to select bias current and driver emitter degeneration resistor. 😕
According Ltspice simulation a simple Push Pull is working better than Diamond buffer and paralleling op amp as unity gain buffer out performs all of them.
Simple push pull performs better with increasing the bias current but Diamond buffer suffers.
For similar bias current Diamond buffer worse than Simple Push Pull Circuit.
Tweaking current and driver emitter degeneration register does improve thd a little bit. But I am clueless as how to properly select bias and degeneration register for any given component.
Any assistance would be greatly appreciated.
simulation file included.
and you have V supply +-12v with bc327/337 output transistors...not sure if they can handle too much heat in the diamond...
@duncan2 @dreamth thanks for reply.
rail voltages and transistors are not critical as it was used only as example, furthermore, lowering the rail voltage and changing the transistor to high power transistors also exhibit similar behavior. 😕
rail voltages and transistors are not critical as it was used only as example, furthermore, lowering the rail voltage and changing the transistor to high power transistors also exhibit similar behavior. 😕
Article and one of the possible schematic attached.
~200 mA idle current are enough for most of the headphones.
Output buffer base bias current also biases opamps output stage.
Inverting connection eliminates common mode error
Input filter effectively decouples this fast amp from the input HF noise
20 MHz unity-gain freq at the higher end of the most of the opamps around
80 dB feedback depth at 20 kHz are at the highest end of the known amps
Unity gain stable
