High-Speed Electrometers for Rocket and Satellite Experiments

Highly stable micromicroammeters capable of measuring currents as low as 5 × 10-14 amperes with a frequency response of at least 30 cps can be realized using directly-coupled electrometer circuitry. The circuit can be packaged in approximately 9 cubic inches and requires less than 100 mw of power. An analysis of the speed of response and signal-to-noise ratio is given in the text and expressions are derived to show the theoretical possibilities of the method and to serve as design guides for realization of the maximum possible performance. Several practical circuits are shown and a summary is presented of the number of circuits which have been used in rocket and satellite exploration.