Based on the design principles of low-noise circuit,a preamplifier circuit structure of nuclear magnetic resonance logging tools was presented.

A preamplifier circuit is also developed,it is applied for amplifying tiny(several millivolt),wide frequency bandwidth(1 K～10 MHz) signals.

This filter is used in preamplifier circuit.

The design of preamplifier circuit based on weak signal detection

The common preamplifiers for the signals of Lidar are not effective as expected,because they have the problem of parameter mismatching with a special Lidar system.

So the pre-amplifier circuit must be designed minutely.

This paper proposes a bias circuit for cascode current mirror in band-gap voltage reference to realize low supply voltage.

The physical performance can be understood explicitly in the equivalent networks,and the judgement of stability functions of every bias circuit could be simply gained.

This paper analyses the quiescent point Q of base electrod potentiometer bias circuit which is evaluted by method of traditional double batteries,and gives a condition which is engineering approximately estimate quiescent point Q of base electrode potentiometer bias circuit.

In this article,we ll present the appli- cation of ku-band GaAs power FET,design of biasing circuit of FET and how to avoid the the self-excitation of power FET.