Precision of lock-in amplifiers as a function of signal-to-noise ratio
D. M. Gualtieri · Review of Scientific Instruments · 1987
The increase in output measurement error of lock-in amplifiers with decreasing input signal-to-noise ratio, which has been shown to be linear over several orders of magnitude [G. T. Gillies and S. W. Allison, Rev. Sci. Instrum. 57, 268 (1986)], is a consequence of the function of a lock-in amplifier as a bandwidth reduction filter.