A 5-GHz, variable gain, SiGe low noise amplifier

Abstract

A bipolar low noise amplifier (LNA) is described in this work. The IC contains the LNA core, an externally programmed bias network, a voltage divider, an LC tank and inductors to set the input impedance. The externally programmed bias network allows the user to select the bias current in an adaptive manner, depending upon the requirements of the individual system. (Low NF, high gain, low consumption etc). The chip can be powered down by sending an appropriate bit stream to the bias network. The tuned amplifier using a parallel LC network provides selective amplification and lower power consumption. The produced gain is 15 dB while the NF is 2.1 dB for moderate power consumption. The IIP3 is -7 dB and the P/sub 1dB/ is -17 dB. The power consumption from a single 5-V supply is 3.4 mA for the low gain mode and 13 mA for the high gain mode.