A New All-Digital Background Calibration Technique for Time-Interleaved ADC Using First Order Approximation FIR Filters

TL;DR

This paper introduces an all-digital calibration method for time-interleaved ADCs using first order approximation FIR filters, significantly improving performance with minimal hardware complexity.

Contribution

It presents a novel calibration technique employing first order approximation FIR filters that reduces circuit complexity and enables real-time calibration of TIADCs.

Findings

Improves SINAD from 45dB to 69dB in simulations.

Enhances measured SINAD from 47dB to 53dB.

Uses only 30 FIR taps for effective calibration.

Abstract

This paper describes a new all-digital technique for calibration of the mismatches in time-interleaved analog-to-digital converters (TIADCs) to reduce the circuit area. The proposed technique gives the first order approximation of the gain mismatches and sample-time mismatches, and employs first order approximation FIR filter banks to calibrate the sampled signal, which do not need large number of FIR taps. In the case of a two-channel 12-bit TIADC, the proposed technique improves SINAD of simulated data from 45dB to 69dB, and improves SINAD of measured data from 47dB to 53dB, while the number of FIR taps is only 30. In the case of slight mismatches, 24-bit FIR coefficient is sufficient to correct 12-bit signals, which makes it easy to implement this technique in hardware. In addition, this technique is not limited by the number of sub-ADC channels and can be calculated in parallel in hardware, these features enable this technique to be versatile and capable of real-time calibration.