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Design >> RF Design >> simulating LNA's PSRR
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Message started by nxing on Dec 26^th, 2007, 10:37am

Title: simulating LNA's PSRR
Post by nxing on Dec 26^th, 2007, 10:37am

Hello everyone,

I have an differential LNA and would like to measure it's PSRR. what I am thinking is that the measuring of a "pseudo single-ended LNA" 's PSRR make more sense. Does anybody can tell me how to set the test bench up?

Thanks

nxing

Title: Re: simulating LNA's PSRR
Post by ACWWong on Jan 2^nd, 2008, 5:50am

You could try a simple ac sweep, with ac magnitude of 1 on the power supply for a small signal measurement of PSRR.

Then look at the ac magnitude on the differential output net. In an ideal schematic, this should be very low. For a more realistic PSRR you'll need to include layout parasitics and mismatch (via monte-carlo), both of which will cause imbalance and hence less common-mode rejection of the supply signal to the differential nets.

For accuracy at higher frequencies, your test bench should include effects such as loading, ESD, bondpads, packaging, pcb etc.

cheers
aw