LOW NOISE AMPLIFIER FOR COMPENSATING NOISE INDEX

摘要

PURPOSE: A low noise amplifier for compensating for a noise index is provided to compensate a noise index characteristic of a low noise amplifier varied according to a thermal variation by using a transistor. CONSTITUTION: An input matching circuit(1) is used for matching an input signal. The first transistor(Q1) is used for amplifying the matched input signal of the input matching circuit(1) and compensating for a variation of noise index according to a variation of temperature. An interstage matching circuit(2) performs an impedance matching operation between a connection line the first transistor(Q1) and a connection line of the second transistor(Q2). The second transistor(Q2) is used for compensating for reduced gains of the first and the second transistors(Q1,Q2). An output matching circuit(3) is used for matching the amplified signals of the second transistor(Q2). A thermal compensation drive circuit(4) outputs a noise index compensating for voltage and a gain compensation voltage to gate stages of the first and the second transistors(Q1,Q2).