NTF zero compensation technique for passive sigma-delta modulator

A novel technique is proposed to compensate zeroes of Noise Transfer Function (NTF) for single loop low pass passive switched capacitor sigma-delta modulator (PSDM). PSDM uses switched capacitor (SC) integrator as a loop filter. Poles of loop filter are zeroes of NTF. The proposed technique for SC integrator shifts the poles of SC integrator from inside the unit circle to z=1 at DC. As a result zeroes of NTF for PSDM also get modified and shifts, which greatly improves the noise suppression and noise-shaping performance. Simulation results in simulink, shows that the technique of proposed SC integrator for 2^nd Order PSDM with 4-bit quantizer having oversampling ratio (OSR) = 32 improves 18dB SNDR over traditional SC integrator.