A LOW-NOISE FET PREAMPLIFIER FOR WIDE-BAND HYDROPHONES

Abstract

The design of a low-noise, field-effect transistor (FET) preamplifier is described, and criteria are given for low-noise operation of relevant FET devices. When used in conjunction with a hydrophone having a sensitivity of -80 dBV/microbar and a capacitance of 60 pF, the design provides a measuring system having a self-noise threshold approximately 10 dB below Sea State 0 from less than 100 Hz to nearly the thermal limit. At the same time, DC bias stability is maintained between 0C and 50C, and voltage gain is 6 dB with frequency response essentially flat from 1 Hz to 1 MHz. Input impedance is approximately 1,000 M ohms at low frequencies, and input capacitance at ultrasonic frequencies is approximately 5 pF.

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 1968
Accession Number
AD0831021

Entities

People

  • Richard I. Allman

Organizations

  • Naval Undersea Warfare Center

Tags

Communities of Interest

  • Advanced Electronics
  • Weapons Technologies

DTIC Thesaurus Topics

  • Acoustics
  • Amplifiers
  • Bandwidth
  • Bipolar Junction Transistors
  • Capacitance
  • Field Effect Transistors
  • Frequency
  • Frequency Response
  • Hydrophones
  • Impedance
  • Low Noise
  • Measurement
  • Resistance
  • Self Noise
  • Semiconductors
  • Transistors
  • Ultrasonic Frequencies

Fields of Study

  • Physics

Readers

  • Acoustics.
  • Electronics Engineering