Hydrophone Preamplifier Optimization-Hybrid Microelectronics for Low-Noise Hydrophones.

摘要

This report presents a dc and low-frequency ac analysis of a low-noise preamplifier design. It also describes how the circuit has been miniaturized to hybrid form and packaged in a TO-99 can. Since the early 1960's, remarkable growth has occurred in the quality of electronic amplifier design for underwater applications. The introduction of the junction field-effect transistor (JFET) resulted in hydrophone preamplifier designs having low-noise, high input impedance, broad bandwidth, and wide dynamic range. The further development of hybrid techniques has allowed these amplifiers to shrink greatly in size and cost. The preamplifier circuit described has been optimized at the Underwater Sound Reference Detachment of NRL into a rugged integrated (hybrid) circuit suitable for low-noise hydrophone applications. Its self-noise is typically -118 dBV for a 1-G ohms input impedance. It operates on a single power supply and has a 100-kHz bandwidth. Equations are developed, suitable for programmable calculators, which analyze the ac and dc conditions in the circuit.