Analysis of the Average Sampling Frequency for Level Crossing Analog-to-Digital Converters

Abstract

This paper introduces two approaches to compute the average sampling frequency (ASF) of ideal level crossing analog-to-digital converters (LC-ADCs). The first is based on Rice's analysis method and can be used in various combinations of Gaussian signals. The second, a direct method, can only be used for narrowband modulated sinusoidal carrier input signals. These analysis results agree very well with computer simulations for ideal LC-ADCs and also highlight the oversampling issue for LC-ADCs (i.e., sampling at rates higher than Nyquist). Wu and Chen previously proposed a Gated LC-ADC to address this oversampling issue. We develop an approximate analysis for the ASF of this Gated LC-ADC by modeling the samples from the un-Gated LC-ADC as a Poisson arrival process. This approximation captures the desired effect of eliminating the oversampling issue reasonably well.