No. Well, if the decimation filter is represented with transistors, it would be possible to use SpectreRF to simulate the transfer functions, but it would be extremely expensive. Generally the decimation filter would be represented as Verilog RTL, and Verilog simulators cannot do AC analyses.

-Ken

I take it back. I don't think its possible to use SpectreRF for this task. SpectreRF applies a small-signal to the input, and a small-signal by definition cannot switch a digital input. Occasionally people use SpectreRF on digital circuits to extract jitter. In that case a small signal can impact the timing of an edge crossing, but in this case you need it to actual switch the input, and a small signal cannot do that.

I think the only answer is some kind of system simulator.

-Ken

No. The definition of a 'small signal' is that the signal is so small that any nonlinear behavior it causes can be and is neglected. By extension, a small signal cannot cross a threshold, and so cannot cause switching behavior. In the case you mentioned, you represent signals with integers. You need a signal to cross a threshold to get an integer value to switch, and small signals never cross thresholds.

In the back of my mind, when I first answered, I was thinking about switched-capacitor circuits. Small-signal analysis generally works fine on switched-capacitor circuits because the signals are continuous values (real valued). However, small signal analysis breaks down at a comparator or quantizer because small signals cannot cross thresholds.

-Ken