A New 5GHz Adaptively-Biased and Variable Gain Low Noise Amplifier

In this paper, a new Low Noise Amplifier (LNA) with adaptive-biasing and variable gain is presented, in which charge pump is used to convert the RF output signal of LNA into a dc control signal, the amplitude of which should be proportional to the input RF magnitude. By using this signal to control bias and gain of LNA simultaneously, the linearity of LNA is greatly improved. In 5GHz frequency, bipolar transistors exhibit better frequency and noise performance, so in this paper, BiCMOS technology is used. The LNA exhibits a noise figure of no more than 3.0dB (in the high gain mode), about 13dBm IIP3 improvement and gain tuning range of more than 15dB.