Improved wideband low distortion cascaded delta-sigma modulator
It has recently become very popular to feedforward the input signal in wideband delta-sigma modulators, so that the integrators only process quantization errors. The advantage being that the actual signal is not distorted by opamp and integrator nonlinearities. In this paper, we focus on improved feedforward techniques for cascaded delta-sigma modulators. A feedforward cascaded structure is presented based on unity-gain signal transfer function (STF) and optimized noise transfer function (NTF) zero placement, using /spl lambda/-analysis. The proposed structure has improved signal-to-noise-ratio (SNR) across the entire input range.