 Reset pedestal variance

Reset pedestal variance is the acquisition-to-acquisition variance of the output offset associated with integrator reset. In a model where the only fluctuating contribution is an opening charge $Q$ on fixed capacitance $C$,Subtracting the mean of the reset charge-injection pedestal removes its constant component, not the random spread. The physical datasheet distinguishes charge-transfer offset from output noise; its charge-transfer limit alone is not a statistical variance specification.^[ref]

Finite blank measurements introduce another contribution. Suppose independent pedestals have mean $\mu$ and standard deviation ${\sigma }_P$. Use $M$ independent zero-input acquisitions to estimate $\mu$, then subtract that same blank sample mean from each of $N$ new signal acquisitions. With a constant signal and no other noise, the corrected mean hasThis variance of a pedestal-corrected sample includes the uncertainty of the shared correction. Its second contribution does not shrink when more signal acquisitions reuse the same blank estimate. Covariance-based uncertainty propagation retains such shared terms.^[ref]

For original stipulated ${\sigma }_P=0.20\mathrm{mV}$, $N=100$ and $M=25$, the corrected mean has standard deviation $0.0447\mathrm{mV}$. An exactly known pedestal mean would give $0.0200\mathrm{mV}$. Repeated zero-input acquisitions at a fixed delay after switching measure the combined pedestal/readout spread; separating its mechanisms requires additional tests. Slow drift or correlations between acquisitions invalidate the independent-sample formula and must enter the measurement model.