US Patent 4,323,852
United States Patent and Trademark Office
University of Iowa Research Foundation (Iowa City, IA, US)
A fast recovery audio amplifier for use in electrophysiology and other neurological tests and techniques relating to nerve and muscle functions. The fast recovery amplifier recovers from overload in less than one millisecond, thus enabling its use in clinical electrophysiology to record time lapses from stimulus to response of less than several milliseconds. The amplifier achieves fast recovery primarily because it eliminates input and interstage coupling capacitors so that the feed-forward path from electrode to output is strictly a DC amplifier.
Walker, David D. Fast recovery electrode amplifier. US Patent 4,323,852 filed November 29, 1979 and issued April 06, 1982. https://ir.uiowa.edu/patents/27