An improved fourth-order band-pass sigma-delta modulator with a novel resonator

Abstract

This paper presents an improved full differential low-voltage fourth-order Ong-band-pass sigma-delta modulator (Ong-BPSDM, proposed by Adrian K. Ong firstly) using a novel resonator based on Salo architecture. Compared with the reported Ong-BPSDM, the proposed fourth-order Ong-BPSDM utilizing a novel double-sampling and double-delay resonator which only needs one op-amp has a better performance with a lower capacitive load and lower power consumption. The performance specifications of the blocks of BPSDM are confirmed by building the behavior model of the system scheme in the environment of Simulink. The circuits are simulated through TSMC0.18μm CMOS process. The modulator achieves a peak signal to noise ratio (SNR) 85.5dB and DR 87dB in the center frequency 20MHz for a 200 KHz bandwidth. The power consumption of the circuits is as low as 27 mW with a 1.8V supply.