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Computer Science and Information Engineering, World Congress on (2009)
Los Angeles, California USA
Mar. 31, 2009 to Apr. 2, 2009
ISBN: 978-0-7695-3507-4
pp: 198-201
A Constant-gm CMOS Operational amplifier with Rail-to-Rail input common-mode voltage range has been designed. The input stage is based on two pairs of single p-channel differential pairs and two identical n-channel source followers as DC level shifters, which realizes rail-to-rail input swing. To attain a constant-gm over the whole common-mode input range, the compensation circuit which is based on processing signal currents has also been designed. The technique is universal in that the constant-gm can be obtained independent of I-V characteristic and is compatible with deep submicron CMOS devices. Using BSIM3v3 model of a standard 0.6µm CMOS process, simulation result shows that the input /output swing of the op amp circuit is rail-to-rail. The op-amp achieves open-loop gain of 113.57dB, unity–gain bandwidth of 11.9MHz and phase margin of 53°.
Rail-to-Rail, class-AB, unity

F. Rui, Z. Wu, C. Wei-Dong and Z. Zhi-Yong, "Design of a Rail-to-Rail Constant-gm CMOS Operational Amplifier," 2009 WRI World Congress on Computer Science and Information Engineering, CSIE(CSIE), Los Angeles, CA, 2009, pp. 198-201.
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