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Design >> RF Design >> Measuring Image Rejection of Mixer
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Message started by vikas on May 10^th, 2005, 11:21am

Title: Measuring Image Rejection of Mixer
Post by vikas on May 10^th, 2005, 11:21am

Can Anybody tell me how to simulate a dual balanced mixer's image rejection? I mean is there a particular analysis in spectre that calculates it automatically. By the way mixer uses a Poly phase filter architecture to suppress image frequency.

Right now i am just taking a Fourier transform of IF output and seeing its magnitude at Image frquency. Somewhere I have read that spectre's FFT function doesn't give you a very accurate results. So let me know if i am doing something wrong or there is a better way to calculate it.

Thanks,
--Vikas

Title: Re: Measuring Image Rejection of Mixer
Post by Ken Kundert on May 10^th, 2005, 8:16pm

The best way to measure image rejection is with a PXF analysis.

FFT routines are generic, they all provide the same level of accuracy. If someone is having trouble with the accuracy of the FFT results, the problem is not with the FFT, but rather the underlying transient analysis. One needs to follow the guidelines given in my book, www.designers-guide.org/Books/dg-spice/.

Using PXF avoids the FFT altogether.

-Ken

Title: Re: Measuring Image Rejection of Mixer
Post by vikas on May 10^th, 2005, 11:42pm

Thanks Ken

--Vikas