Could someone help to analyse the circuit above, which is a single common emitter amplifier. And for the purpose of larger voltage gain, a current mirror building block is applied as active load. But I could not analyse how it work for larger voltage gain, and even be confused with current variation when there is a input signal applied.
when there is no input signal Ic2 is approximately equal to IR, and will be constant also Ic1 = Ic2
when there a small input signal, say Δib, so will be Δic1, and the Q1 collector current Ic1 now will be Ic1 + Δic1 but Ic2 is still unchanged, that is to say when applied input signal, Ic2 will not be equal to Ic1, that is what has confused me. Would someone help to explain it ? Thank you!