Title :
A 135-μW 0.46-mΩ/√Hz thoracic impedance variance monitor with square-wave current modulation
Author :
Chih-Chan Tu ; Feng-Wen Lee ; Dong-Feng Yeih ; Tsung-Hsien Lin
Author_Institution :
Nat. Taiwan Univ., Taipei, Taiwan
Abstract :
A low-power high-resolution thoracic impedance variance (TIV) monitoring circuit is presented. The TIV information is extracted by injecting a square-wave modulated current to the body. The resulted voltage is then demodulated by a proposed delayed-sampling technique. This proposed technique solves the gain-error issue occurred in prior square-wave modulated architectures. Furthermore, compared with sine-wave modulation, the proposed TIV monitoring circuit is more power efficient. Fabricated in a 0.18-μm CMOS, this chip draws 75 μA from a 1.8-V supply. The equivalent input-referred impedance noise density is only 0.46 mΩ/VHz.
Keywords :
CMOS integrated circuits; biomedical electronics; electric impedance imaging; low-power electronics; modulation; CMOS; TIV information; current 75 muA; delayed-sampling technique; gain-error issue; low-power high-resolution TIV monitoring circuit; low-power high-resolution thoracic impedance variance monitoring; power 135 muW; size 0.18 mum; square-wave modulated current; voltage 1.8 V; Current measurement; Demodulation; Immune system; Impedance; Monitoring; Noise;
Conference_Titel :
Solid-State Circuits Conference (A-SSCC), 2014 IEEE Asian
Conference_Location :
KaoHsiung
Print_ISBN :
978-1-4799-4090-5
DOI :
10.1109/ASSCC.2014.7008921
