TITLE:
Low-Noise Front-End Receiver Dedicated to Biomedical Devices: NIRS Acquisition System
AUTHORS:
Ahmad Chaddad
KEYWORDS:
NIRS, TIA, LPF, CMOS
JOURNAL NAME:
Circuits and Systems,
Vol.5 No.8,
August
8,
2014
ABSTRACT: This paper concerns the design and the implementation
of a fully integrated front-end intended to Near-Infrared Spectroscopy System (NIRS)
acquisition system. A low-noise transimpedance amplification (TIA) circuit followed
by adjustable cut-off frequency and a low-pass filter (LPF) was implemented in order
to decrease noise circuit of NIRS detectors. For TIA, a single ended common source,
common gate input stage based on a cascode structure is used to get a higher gain-bandwidth closed-loop transimpedance amplifier. To enhance the circuit noise performance,
a single feedback transistor technique is used, compared to passive feedback, to
achieved high quality data from NIRS acquisition channel. The proposed LPF combines
two control methods to adjust the low cut-off frequency. Simulation results show
a TIA gain of 104.2 dBΩ, ?3dB bandwidth of 19 MHz and an equivalent input noise
current spectral density of 446 fA/√Hz. LPF filter exhibits a relatively constant
noise 201nV/√HzQUOTE√Hzfrom 0 Hz to 700 KHz and linearity performance
over its entire tuning range. The proposed front-end of NIRS preamplifier is implemented
using 0.18 μm CMOS technology.