Lucky-Luka
Member
Hi all
I've tried the output stage of an amplifier with +-14V output swing and 10ohm resistive load.
For project reasons I have to use those two transistor as output transistor.
I thought that the current source value just needed to be greater than the maximum base current at emitter current=1.4A (peak current value).
The beta gain of those transistor are 66 and 73 (from LTSpice parameters) so I did Ie_peak/66=Ib_peak=21mA.
I left 4mA for the Vbe multiplier and I thought I was ok.
With a 25 mA current source I get a lot of distortion.
Rising current source value to 75mA improves the distortion a lot!
I don't understand how I can choose that value. Just trying to increasing it and looking at the result?
Is there a way to improve this circuit working the biasing?
I've tried the output stage of an amplifier with +-14V output swing and 10ohm resistive load.
For project reasons I have to use those two transistor as output transistor.
I thought that the current source value just needed to be greater than the maximum base current at emitter current=1.4A (peak current value).
The beta gain of those transistor are 66 and 73 (from LTSpice parameters) so I did Ie_peak/66=Ib_peak=21mA.
I left 4mA for the Vbe multiplier and I thought I was ok.
With a 25 mA current source I get a lot of distortion.
Rising current source value to 75mA improves the distortion a lot!
I don't understand how I can choose that value. Just trying to increasing it and looking at the result?
Is there a way to improve this circuit working the biasing?