Simultaneous STF and NTF Estimation in CTΔΣ Modulators with ARMA-Model

One main concern for a continuous-time (CT) multi-stage noise-shaping (MASH) delta sigma (ΔΣ) analog to digital (ADC) is how to make the digital filtering responses match the analog transfer functions of the sub-loop. Since non-ideal factors of CTΔΣ modulator greatly affect analog transfer functions, the accurate estimation of the signal transfer function (STF) and quantization noise transfer function (NTF) affects the final performance of the ΔΣ ADC. In this paper, STF and NTF are simultaneously estimated for CT MASH 0-3-0 ΔΣ ADC with autoregressive and moving-average (ARMA) Model. The proposed method called digital quantization noise leakage reduction algorithm (DQNLRA) could also deal with excess-loop-delay (ELD) and finite gain and bandwidth of op-amp in CTΔΣ modulator.