sheldon
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Svensl,
If the goal is just to lower the noise floor why not just increase the length of the FFT. Tested this recently for an Oversampling ADC.
1) Baseline simulation was 4096 conversions with an input frequency of 7/4096.
2) Re-ran the simulation with a 4x longer simulation and the same input frequency.
The noise floor of the second simulation was signficantly lower, normally we would expect the noise floor to be 10 log 4 better or about 6dB better. Since data from oversampling ADCs need to be windowed anyway, the only penalty is longer simulation time.
This increasing the number of time points is complementary to the approach Eugene suggests. Strobing eliminates the interpolation error in the data. Increasing the number of FFT points, decreases the resolution bandwidth of the FFT. Since the noise in fixed, decreasing the bandwidth decreases the noise, noise(V/rt Hz) * bandwidth(rt Hz). Since noise is uncorrelated, noise decreases by 3dB/oct.
So if you runnning the simulation with MATLAB, this is probably not an issue. If you are running SPICE, this may be more problematic.
Best Regards,
Sheldon
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