Negative Feedback Electrometer Circuit
Robert A. Spangler · Review of Scientific Instruments · 1962
An electrometer circuit, utilizing a commercially available differential operational amplifier, is described and its basis of operation briefly analyzed. By virtue of the negative feedback configuration employed, interelectrode potential relationships in the electrometer tube are maintained virtually constant, thus providing highly stable performance, linear gain characteristics, and a high effective input impedance. Provision for compensation of nonideal amplifier characteristics and input capacitance neutralization is included.