title: A small-area low-power current readout circuit using two-stage conversion method for 64-channel CNT sensor arrays.
abstract: In this paper, a small-area and low-power current readout circuit with a novel two-stage conversion method is presented for 64-channel CNT (carbon nanotube) sensor arrays. In the first stage, current of each CNT sensor is amplified by 64 active input current mirrors (AICMs). In the second stage, the amplified current is converted to a voltage level through the shared variable gain amplifier (S-VGA). Then the S-VGA output is digitalized by successive approximation register analog-to-digital converter (SAR-ADC). The proposed readout circuit significantly reduces chip area and power consumption, since VGA is shared over 64 channels and passive elements are used only in S-VGA. Fabricated chip area is 0.173 mm(2) in 0.13 μm CMOS technology. Measured power consumption and linearity error are 73.06 μW and 5.3%, respectively, at the input current range of 10 nA-10 μA and conversion rate of 640 samples/s. A prototype real-time CNT sensor system was implemented using the fabricated readout circuit, and successfully detected alcohol reaction.
authors.affiliation: School of Electronic Engineering, Soongsil University, Seoul 156-743, Korea. youngsan@ssu.ac.kr
authors.forename: Young-San
authors.initials: YS
authors.lastname: Shin
authors.forename: Seongsoo
authors.initials: S
authors.lastname: Lee
authors.forename: Jae-Kyung
authors.initials: JK
authors.lastname: Wee
authors.forename: Inchae
authors.initials: I
authors.lastname: Song
mesh_terms: D000438:Alcohols / Q000737:chemistry; D000669:Amplifiers, Electronic; D000703:Analog-Digital Conversion; D001672:Biocompatible Materials / Q000737:chemistry; D015374:Biosensing Techniques; D003198:Computer Simulation; D004553:Electric Conductivity; D011211:Electric Power Supplies; D004867:Equipment Design; D037742:Nanotubes, Carbon / Q000737:chemistry*; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D012825:Silicon; D013696:Temperature; D013997:Time Factors
chemical_list: D000438:Alcohols; D001672:Biocompatible Materials; D037742:Nanotubes, Carbon; D012825:Silicon