hi, i have a few questions here please help, thanks in advance.
Please check this 1 stage op-amp:
1) simulation gives differential voltage gain Av=36dB which is too far away from hand-calculation 58dB, why ?
NOTE : with current mirror load, Av=gm (Ron || Rop), gm depends on Ic (≈56uA) which is gm=0.00215 ; Ron & Rop depands on VA/Ic which give total Rout=388kΩ ; Av=824=58dB
2) does impedance matching for single-ended output and input of emitter follower important ? what is tolerance for this matching ?
3) when i switch between input terminal, i can still get the same stable result, why?
4) simulation for open-loop (removed resistor divider and follower), gain is just slightly higher , around 37.5dB. That means the loop-gain is 1.5dB, but calculation is around 21dB from AOL*β=37.5db*14k/(14k+11k), why so much different ?
thank you so much for helping