SYMMETRICAL_BIOPLAR

Published:2009/7/13 21:59:00 Author:May | From:SeekIC

Circuit uses transistor feedback, with cument returned to opamp summing point through emitter-followers Q1 and Q2. When output E0 rises to positive voltage high enough so tap on R4, makes Q1 turn on, output of A1 is limited to value corresponding to setting of R4. Q2 performs similar limiting function for negative swings of input signal. R4 sets limiting level for both polarities, for variable symmetrical limiting. Transistors and opamps shown are selected for high-speed operation.For single-polarity limiting, insert large resistance RB in base lead of remaining transistor to prevent it from conducting heavily on output voltage swings.-W. G. Jung, IC Op-Amp Cookbook, Howard W. Sams, Indianapolis, IN, 1974, p 203-204.



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