OpAmp transient simulation problem

[vilemk]

Hello,

I have problem with Opamp transient simulation. I´ve designed several one stage structures (folded, telescopic, symetrical CMOS) and all made same problem. In attachment file is simulation connection - R ratio is 1. So If I have input sinus amplitude 1 V, output amplitude is not 1 V but a little bit smaller. I don´t know, where is mistake. It is only in one stage structures, two stage is ok. Could somebody help me?

 

[LvW]

The gain of an opamp with feedback always is slightly smaller than indicated by the R ratio - depending on the opamp open loop gain.
Don't you know Blacks classical formula for feedback?

 

[vilemk]

Firstly, thank you for your answer...Yes I know it. But gain of this opamps is sufficiently (approx. 75 dB). When I give ideal VCVS (gain = 1) to output, it is ok. Maybe output current make this worst, but its small enought.....