Hello,

I have a design for 2nd order Sigma-Delta ADC.  I have read Ken's paper on simulation Switch Capacitor Filters.

The output of my ADC is a 1-bit stream. The output of the 2nd integrator is clocked through  a DFF and then goes into a 1-bit quantizer. The output of the 1-bit quantizer feeds into the input stage for subtraction.



What I want to know is the following:

1. If I want to simulate the transfer function using PSS and PAC, do I have to use the ideal sample and hold block Ken talks about.

2. Also for noise using PNOISE will it be sufficient to use tdnoise and add sepcific point time as the time of the edge of the 1-bit stream.

3. If I want to estimate the PSRR of the ADC, do I still have to use the ideal S/H circuit or I can use the raw output data. What frequency has to be swept and type absolute or relative. Should I have freqaxis as out or In.

4. How can I run FFT on the 1-bit stream of the ADC output in SpectreRF. I want to do this to check for  idle tones due to quantization noise.

I will really appreciate your help.

ic_engr