OPAMP_ELECTROMETER

Published:2009/7/15 3:32:00 Author:Jessie | From:SeekIC

Use of FET input keeps input bias current down to 20 femtoamperes, with common-mode input resistance of 1015 ohms. Uses Analog Devices AD 832 dual JFET Q1-Q2 in source-follower connection, with low-cost general-purpose AD 3958 dual FET generating operating current and providing bootstrapping for Q1-Q2. Article covers guarding techniques used to minimize leakage currents.-J. Dostal, Electrometer Boasts Low Bias Current, EDN Magazine, Jan. 20, 1977, p 90 and 92.



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