Statistical behavior of a comparator with weak repetitive signal and additive white Gaussian noise

Digital averaging technique is widely used in weak signal detection. The weak signal buried in strong noise is normally digitized with a multi-bit analog-to-digital converter (ADC) before the averaging. When using large number of averaging, the digitization can be accomplished by a 2-level comparator, instead of a multi-bit ADC. In this paper, we studied the statistical properties of ADCs with additive white Gaussian noise (AWGN) input. Our analysis shows that, with low signal-to-noise ratio (SNR) input, a comparator introduces 20% amplitude SNR loss compared with a fine multi-bit ADC, which can be mostly recovered with a post filter. It also shows that the comparator is linear and insensitive to input offset with low SNR input and AWGN.