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Constant Transconductance Bias Circuit with an On-Chip Resistor

TitleConstant Transconductance Bias Circuit with an On-Chip Resistor
Publication TypeConference Paper
Year of Publication2006
AuthorsTalebbeydokhti, N., P K. Hanumolu, P. Kurahashi, and U. Moon
Conference Name2006 IEEE International Symposium on Circuits and Systems
Pagination2857 - 2860
Date Published05/2006
Conference LocationIsland of Kos, Greece

A method to generate stable transconductance (gm) without using precise external components is presented. The off-chip resistor in a conventional constant-gm bias circuit is replaced with a variable on-chip resistor. A MOSFET biased in triode region is used as a variable resistor. The resistance of the MOSFET is tuned by a background tuning scheme to achieve the stable transconductance that is immune to process, voltage and temperature variation. The transconductance generated by the constant-m bias circuit designed in 0.18µm CMOS process with 1.5V supply displays less than 1% variation for a 20% change in power supply voltage and less than ±1.5% variation for a 60 ◦C change in temperature. The whole circuit draws approximately 850µA from a 1.5V supply.