Channel Mismatches Correction in Time-Interleaved ADCs Based on Hybrid Filter Bank Reconstruction

Time-interleaved analog-to-digital converter (TIADC) is an efficient way to achieve higher sampling rate for medium-to-high resolution applications. The performance of a TIADC suffers from the mismatch errors among the sub-channels. This paper presents a method to estimate the channel mismatches using the sub-channels output data. The proposed method introduces an equivalent transfer function for each channel to model and estimate the mismatch errors. A Hybrid filter bank (HFB) structure is used to both model the TIADC and reconstruct the desired uniformly sampled sequence based on the perfect reconstruction conditions of the HFB system. A four-channel 12-bit 400MHz TIADC has been implemented in hardware to verify the proposed calibration method. The measured results show that the Spuriousfree dynamic range (SFDR) can be improved up to 74dB after being corrected with 64-tap Finite-impulse response (FIR) filters.