A 6th-Order Quadrature Bandpass Delta Sigma AD Modulator Using Dynamic Amplifier and Noise Coupling SAR Quantizer

Abstract

This paper presents a 6th-order quadrature bandpass delta sigma AD modulator (QBPDSM) with 2nd-order image rejection using dynamic amplifier and noise coupling (NC) SAR quantizer embedded by passive adder for the application of wireless communication system. A novel complex integrator using dynamic amplifier is proposed to improve the energy efficiency of the QBPDSM. The NC SAR quantizer can realize an additional 2nd-order noise shaping and 2nd-order image rejection by the digital domain noise coupling technique. As a result, the 6th-order QBPDSM with 2nd-order image rejection is realized by two complex integrators using dynamic amplifier and the NC SAR quantizer. The SPICE simulation results demonstrate the feasibility of the proposed QBPDSM in 90 nm CMOS technology. Simulated SNDR of 76.30 dB is realized while a sinusoid −3.25 dBFS input is sampled at 33.3 MS/s and the bandwidth of 2.083 MHz (OSR=8) is achieved. The total power consumption in the modulator is 6.74 mW while the supply voltage is 1.2 V. key words: quadrature bandpass delta sigma modulator, image rejection, SAR quantizer, noise coupling, ring amplifier, complex integrator