Design of low noise high power RF amplifier using bipolar junction transistors

摘要

The radio frequency amplifiers differ from audio frequency amplifiers in the choice of values and the circuit elements. In most applications of the microwave amplifiers not only high amplification is desirable, but the usable bandwidth should be as great as possible. The ordinary amplifiers can not operate at microwave ranges because of their inherent parasitic parameters and thus, it is necessary to design a Microwave Amplifiers, which is free from above bottlenecks. This work concerns with the design of low noise microwave amplifier using Transistors. Microwave transistors are essentially scaled-down version of low frequency transistors. They find applications as local oscillators for radars and as radio frequency sources for low power transmitters apart from low noise microwave amplifiers. Most microwave bipolar transistors are generally Silicon n-p-n devices. The design objective in this work is of two fold: ud1) Determination of scattering parameters from a given set of power gains and noise figure. The design is, however, based on a single operating frequency. This, of course, can function well within a small band of frequencies with a centre frequency equals to the operating frequency. ud2) Determination of performance index of a microwave amplifier, that is, Noise Figure(F), Gain(gp), Voltage standing wave ratio at input and at out put. Also the detail calculations are presented in chapter-3; it is worthwhile to mention that the design problem undertaken satisfies the need of an amplifier, which can be used for microwave applications.