Title :
A NIR CMOS preamplifier with DC photocurrent rejection for pulsed light source
Author :
Wong, Alex K Y ; Pun, Kong-Pang ; Zhang, Yuan-ting ; Leung, Ka Nang
Author_Institution :
Dept. of Electron. Eng., Chinese Univ. of Hong Kong, Hong Kong
fDate :
Nov. 29 2006-Dec. 1 2006
Abstract :
A micro-power transimpedance amplifier is presented to acquire modulated optical signal for heart-rate measurement. The circuit is composed of a transimpedance amplifier (TIA), a sample-and-hold (S/H) circuit, an error amplifier and a current-sink transistor, configured in a feedback loop to reject DC photocurrent generated from photodiode, which varies from person to person. To reduce power consumption, the LED is pulsed and thus the input to the TIA is a modulated current pulse. The proposed circuit is designed to accurately reject the average of the original continuous time signal, rather than that of the pulsed signal. This is achieved by inserting an S/H stage between the TIA and error amplifier. Simulation results show that the circuit works properly from a 2-V power supply and has a rejection range from 40 muA to 95 muA.
Keywords :
CMOS integrated circuits; light emitting diodes; light sources; photoemission; preamplifiers; DC photocurrent rejection; LED; NIR CMOS preamplifier; current 40 muA to 95 muA; current-sink transistor; error amplifier; micro-power transimpedance amplifier; pulsed light source; sample-and-hold circuit; voltage 2 V; Feedback circuits; Light sources; Optical amplifiers; Optical modulation; Optical pulses; Photoconductivity; Preamplifiers; Pulse amplifiers; Pulse modulation; Semiconductor optical amplifiers;
Conference_Titel :
Biomedical Circuits and Systems Conference, 2006. BioCAS 2006. IEEE
Conference_Location :
London
Print_ISBN :
978-1-4244-0436-0
Electronic_ISBN :
978-1-4244-0437-7
DOI :
10.1109/BIOCAS.2006.4600295
