happyday
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Dear all, I have a question about using PSS and Pnosie to simulate an auto-zeroed SC integrator in sigma-delta modulator. I want to know the 1/f noise corner of an auto-zeroed SC integrator I have tried three different ways.
All simulations are done with zero input and 5V clock signal.
1) SC integrator (with Cs and Cint), normal connection: Choosing noise type to "time domain", I can only plot output noise. Thus I need to divided it by the transfer function.
Thus I simulated the PAC simulation, however I can not get the expected transfer function of the SC integrator. I use SC CMFB. If I change it to CT CMFB. I can get the PAC transfer function I want.
2) SC integrator (with Cs and Cint), close loop by adding an S&H to feedback the output of the integrator to the input during the next integration phase.
This is described in Ken's paper about device noise simulation in Sigma-delta. Since it's a unity gain feedback, the output noise will equal to the input noise. PAC transfer function = 1 at low frequency
3) SC integrator (with Cs and Cint), normal connection, and then followed by a S&H, not close loop. This technique is described in Ken's paper about SC-filter. I only sample the point at the end of the integratotion phase.
For these three techniques, I got different 1/f noise corner, I am not sure which one is the correct way to simulate the input inferred noise for auto-zeroed SC integrator.
Is there anyone who knows about this problem? Thank you very much in advance and I appreciate it.
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