help about a chopper amplifier

[hongmy]

chopper amplifier

Hi,all
I'm designing a chopper amplifier. when i read a papaer by Analog Devices , I'm puzzled. it said:
' Chopper-stabilized amplifiers solved the bandwidth limitations by combining the chopper amplifier (used as a stabilizing amplifier) with a conventional wideband amplifier that remained in the signal path. However, simple chopper stabilized designs are capable of inverting operation only since the stabilizing amplifier is connected to the non-inverting input of the wideband amplifier. '

who can tell me why?

 

[hongmy]

and it said:
'Virtually all modern IC chopper amplifiers actually use an auto-zero approach utilizing a two (or more) stage composite amplifier structure similar to the chopper-stabilized scheme. One stage provides nulling action, while the other provides wideband response. Together, the two stages provide very high voltage gain as they are connected in series. '

is that true? In my sense, chopper is a so good technique, why didn't it gain a good development?

 

[FvM]

chopper is a so good technique, why didn't it gain a good development

Basic chopper amplifiers have serious limitations, particularly regarding signal bandwidth. Also the first generation of autozero amplifiers (e.g. Intersil ICL7600) was far from acting as an ideal amplifier. AC input around the chopper frequency caused large offsets with these devices. Recent "zero drift" or chopper stabilized amplifiers still can't compete with high quality standard OP at some parameters, e.g. common mode rejection, noise, spurious signals. But they are superior in special applications.

 

[hongmy]

3k FvM for your help

and who can tell me about the first question.