[Moved]: Problems in simulation noise of amplifier
时间：03-25
整理：3721RD
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Hi everyone.
I am using Cadence IC5 to simulate a 2 stage opamp noise.
What I want is to find the corner frequency where 1/f noise equals thermal noise.
The problem is that from "direct plot->main from->noise" I can see the 10dB/decade roll till 1kHz, then the power begins to keep decreasing with 30 dB/decade and never stop. I think the problem is thermal noise is not showing on the plot.
But by using "print->noise summary" I do see the percentage of flicker noise decreases and about equal to thermal noise in about 5MHz.
Can someone tell me where I am wrong and how I can get the plot I want?
I am using Cadence IC5 to simulate a 2 stage opamp noise.
What I want is to find the corner frequency where 1/f noise equals thermal noise.
The problem is that from "direct plot->main from->noise" I can see the 10dB/decade roll till 1kHz, then the power begins to keep decreasing with 30 dB/decade and never stop. I think the problem is thermal noise is not showing on the plot.
But by using "print->noise summary" I do see the percentage of flicker noise decreases and about equal to thermal noise in about 5MHz.
Can someone tell me where I am wrong and how I can get the plot I want?
Probably the bandwidth of your opamp is smaller than flicker noise corner frequency?
Exactly! I figured out later.
Thanks for your answer anyway!