Linear LMS compensation for timing mismatch in time-interleaved ADCs

Abstract

The time-interleaved architecture permits implementing high frequency analog-to-digital converters (ADCs) by multiplexing the output of several time-shifted low frequency ADCs. An issue in the design of a time-interleaved ADC is the compensation of timing mismatch, which is the difference between the ideal and the real sampling times. In this paper we propose a compensation method which, as opposite to other approaches, do not make a bandlimited assumption on the signal to be sampled. The proposed compensation is designed in a statistically optimal sense, to minimize the power of the reconstruction error in the samples, for a given input signal power spectrum. Due to the non-bandlimited assumption, perfect reconstruction is not possible in general. However, if the input signal is bandlimited, the proposed method achieves perfect reconstruction, if no constraints are made in the order of the compensation. Simulation results show that the proposed compensation outperforms the other methods, in terms of the reconstruction error power, for a given fixed compensation order, except for signal having large zero regions in their power spectrum. A generalization of the proposed method solves this drawback, and will be addressed in a journal version.