High linear integrated LC filter for a continuous-time bandpass sigma-delta ADC

The loop filter is one of the most difficult parts to implement in bandpass continuous-time sigma-delta modulators. LC filters have been presented as a filtering alternative for modern integrated radio transceivers. It allows the implementation of on-chip, high Q filters with high resonance frequencies. This paper describes the implementation of a parallel sixth-order bandpass sigma-delta modulator in 0.35mum CMOS technology. The continuous-time loop filter is based on an integrated LC tank and an improved linear transconductance amplifier. Simulation results show that good noise shaping performances is reached