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Design >> Analog Design >> How to design opamps with less specs
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Message started by avlsi on Aug 30^th, 2006, 2:17am

Title: How to design opamps with less specs
Post by avlsi on Aug 30^th, 2006, 2:17am

Hi all,

This seems to be funny. But I have a reason, all these days I was getting specs and was designing opamps. They were enough to know my W/L.

Now, I am facing a problem of generating specs and designing.

Let me tell u in detail. I need to design an opamp with the follwoing specs in 0.18 um technology

Open Loop Gain 90 dB
Phase Margin 60 degrees - I assumed ( no specs)
Unity Gain Frequency 1 M Hz - I assumed ( no specs)
ICMR 0.8-1.6
OCMR 0.15-1.65
VDD =1.8
Cload = 25 p F
RLoad = 1 Mega Ohm

The biggest problem, I am operating my system @ DC. So, I am not bothered about AC behaviour settling time. Slew rate is also not that important

I donot know how to decide the currents. I am designing a two stage miller opamp.

Please help me on this.

Thanks in advance.