Title :
A second-order sigma-delta modulator with built-in VGA to improve SNR and harmonic distortion
Author :
Li, Xiaopeng ; Ismail, Mohammed
Author_Institution :
Analog VLSI Lab., Ohio State Univ., Columbus, OH, USA
Abstract :
A modified architecture of the second-order switched capacitor modulator is proposed. A simple four-transistor variable gain attenuator is included in the architecture which continuously adjusts the reference voltage of the quantizer feedback. This improves the output SNR for small signal input and reduces the harmonic distortion for large signal input. Simulation results show that it achieves higher dynamic range and lower harmonic distortions compared with the traditional architecture
Keywords :
attenuators; circuit feedback; harmonic distortion; quantisation (signal); sigma-delta modulation; switched capacitor networks; SNR; built-in VGA; dynamic range; four-transistor variable gain attenuator; harmonic distortion; output SNR; quantizer feedback; reference voltage; second-order sigma-delta modulator; second-order switched capacitor modulator; Analog-digital conversion; Attenuators; Delta-sigma modulation; Dynamic range; Feedback; Gain; Harmonic distortion; Operational amplifiers; Signal to noise ratio; Voltage;
Conference_Titel :
VLSI, 1999. Proceedings. Ninth Great Lakes Symposium on
Conference_Location :
Ypsilanti, MI
Print_ISBN :
0-7695-0104-4
DOI :
10.1109/GLSV.1999.757460
