nobody wrote on Mar 19th, 2009, 12:46am:Thanks for your reminding. Actually the large signal gain is measured when output is in transition and the input ranges from -10mV to 10mV
@ that time when a large signal is applied from -1V to 1V. I tried ways to increase all length or add a booster but the large signal was the same. However, when a small differential signal like 300mV or an input voltage from -10mV to 10mV is applied, a high gain can be expected. One more question shows up.
Why the gain is different even the gain is measured when vid is between -10mV to 10mV under large and small input signal ?
for such a high gain amp with limited output swing at 3V supply, i would assume its input linear range to be between +/-1.5mV at maximum. +/-10mV is still too large to be considered as small signal, let alone 300mV (it is way too huge). another possible error is, you need to guarantee the same step size (and small enough) for dc sweep through different range, in order to get the correct information.