Jerry Kwon
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Hello HK2004!
I read your problem so I'd like to suggest something. First of all, sometimes there are faults with transient simulation results because of step problem. Thus, I think, more point sizes make FFT's SNR reduce. If you can get text output, how about you perform following as: Using Matlab-> command box -> (typing) psd(output,length(output),frequency) and then you can see the exact specrum you want.
Good luck!
Best, Jerry Kwon
In Cadence , I run transient analysis for model based SDM circuit and strobe the output. My setting is like this: quantizer clock frequency: 64M or period 15.625ns skipstart: 319.5ns = 312.5+7ns. the 312.5 is 20 cycle for skipping the inital data. The quantizer is rising edge triggered. So 7ns is used to settle. The problem is like this: if I store 8192 data , the FFT results shows the SNR is 48dB. But if I store 4096 data, the FFT results shows the SNR is 79dB that is expected. FFT operation is performed by matlab, and hann window is used. Does anyone help on this? Thanks a million.
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