A 2-1 cascaded hybrid continuous-discrete time sigma-delta modulator

This paper describes a new 2-1 cascaded hybrid sigma delta modulator where the discrete time filter is realized with fully differential current conveyor. The hybrid convertor, which is a combination of an analog integrator and two digital integrators, offers an increased dynamic range, helps make the resulting high-order sigma delta modulator stable and reduce power consumption comparing with discrete time realization for the same topology. The convertor has been designed in a 0.18um TSMC technology and achieves a maximum signal to noise ratio 87dB in a 500 KHz bandwidth and dissipates 34mW at 1.8V power supply.