Calibration and equalization methods for mismatch errors in a high frequency two-channel time-interleaved ADC

An M-channel time-interleaved (TI) analog-to-digital converter (ADC) which is a combination of M ADCs in parallel increases the sampling frequency by a factor of M. Although TI ADC seems to be a good solution for increasing the sampling rate, embedded system designers utilizing TI ADCs face with multiple matching problems causing distortions in the sampled signal. These problems are offset, gain and sample-time mismatches introduced in the process of interleaving. In this paper, an offline calibration technique to compensate mismatch errors in a 2-channel gigasample per second (GSPS) TI ADC is presented. Moreover, an equalization method estimating and compensating these mismatch errors in a 2-channel TI ADC is introduced. This equalization method, which can be implemented with low hardware overhead, requires only that the input signal is band-limited to the Nyquist frequency of the 2-channel TI ADC.