Digital Background Calibration of Analog Errors in Passive Sigma-Delta Modulator

This paper proposes a digital adaptive calibration to compensate passive ΔΣ modulator error based on output-referred error model of passive integrator. The passive integrator transfer function, which leads to gain and phase errors, degenerates the performance of modulator due to signal attenuation in modulator loop. To identify the adaptive filter factors, a 1-bit pseudo-random noise test signal is applied to the input of the passive ΔΣ modulator. The error factors are identified by making correlation between output and test signals. The simulations show the effectiveness of the intrinsic error compensation of the modulator.