High-Resistance Resistor Consisting of a Subthreshold CMOS Differential Pair

Shin'ichi ASAI  Ken UENO  Tetsuya ASAI  Yoshihito AMEMIYA  

IEICE TRANSACTIONS on Electronics   Vol.E93-C   No.6   pp.741-746
Publication Date: 2010/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E93.C.741
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
CMOS,  integrated circuit,  resistor,  high resistance,  differential circuit,  subthreshold,  

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We propose a CMOS circuit that can be used as an equivalent to resistors. This circuit uses a simple differential pair with diode-connected MOSFETs and operates as a high-resistance resistor when driven in the subthreshold region of MOSFETs. Its resistance can be controlled in a range of 1-1000 MΩ by adjusting a tail current for the differential pair. The results of device fabrication with a 0.35-µm 2P-4M CMOS process technology is described. The resistance was 13 MΩ for a tail current of 10 nA and 135 MΩ for 1 nA. The chip area was 105 µm110 µm. Our resistor circuit is useful to construct many high-resistance resistors in a small chip area.