Chopper-stabilized high-pass sigma delta modulator utilizing a resonator structure

A chopper-stabilized high-pass sigma delta modulator (SDM) utilizing a resonator structure for the reduction of low-frequency noise, such as dc offset, thermal drift, and 1/f noise, is presented. The high-pass SDM has a zero of a noise transfer function at half of the sampling frequency and is stabilized by chopper modulation. Since the first integrator of the proposed modulator has a large closed-loop gain, no pre-amplifier is required even when the input signal is small, which is suitable for low-power applications. The signal-to-noise ratios (SNRs) and power dissipations of a high-pass modulator and a conventional modulator have been numerically analyzed.