Comprehensive digital correction of mismatch errors for a 400-msamples/s 80-dB SFDR time-interleaved analog-to-digital converter

Abstract

Comprehensive digital calibration of a high-speed and high-resolution time-interleaved analog-to-digital converter (TIADC) is described. A channel transfer function, which incorporates all linear errors between analog input and digital output, is measured for each channel by applying a series of sinusoids. A set of finite-impulse response (FIR) filters designed by the weighted least squares principle provides frequency-dependent mismatch correction so that the spurious-free dynamic range (SFDR) is no longer limited by channel mismatches. A four-channel TIADC prototype with 14-bit resolution and 400-MHz aggregate sampling rate was built to verify the proposed correction method. Uncalibrated SFDR was below 50 dB. After mismatch correction with 61-tap FIR filters, 80 dB of SFDR was achieved up to /spl sim/175 MHz of input frequency.