Abstract: Discusses in detail the circuit, device and lithographic design of a low-noise integrated preamplifier which can be used for various sensors, especially for acoustic sensors. The preamplifier is fabricated through standard p-n isolated technology and its performance is presented. Its characteristics of having low -noise, broad band, etc are gained by means of selecting optimum collect current and reducing noise in the circuit design. Its equivalent input noise voltage average is less than 2.9nV/ , and its product of gain and band -width is as high as 12MHz.