Recursive Filters for Time-Interleaved ADC Mismatch Compensation

Time-interleaved analog-to-digital converter (TIADC) mismatch compensation filters are traditionally finite impulse response (FIR) filters. The advantages of using FIR filters are that FIR filters are inherently stable and that the design techniques are readily available. This paper demonstrates that infinite impulse response (IIR) filters can be designed to compensate for the mismatch error in the TIADC. Two methods for achieving stability are introduced; one is by increasing the group delay and the other is by constraining the magnitudes of the denominator coefficients. Simulation examples show that, for a given spurious frequency power, the proposed IIR TIADC compensation filter yields about 30% saving in the total number of multiplier coefficients when compared to the conventional FIR TIADC compensation filter. Important aspects of the IIR compensation filter such as noise propagation, performance in the presence of identification error, filter redesign to cope with mismatch drifting are also investigated.