Gain and offset mismatch calibration in multi-path sigma-delta modulators

In this paper we propose a digital background adaptive calibration technique for correcting offset and gain mismatches in multi-path sigma-delta (ΣΔ) modulators. The proposed technique allows us to cancel the spurious tones introduced by offset and gain mismatches among the paths only by processing the digital output, without interfering with the operation of the modulator. This solution is also effective for any other time-interleaved A/D converter topology. Simulation results on a four-path band-pass ΣΔ modulator demonstrate the effectiveness of the proposed calibration technique, which allows us to achieve significant improvements of the SNR and the SFDR in the presence of mismatches.