Highly reconfigurable single-ended low noise amplifier for software defined radio applications

Abstract

A reconfigurable low noise amplifier with variable gain, bandwidth and center frequency is described. In order to achieve this degree of reconfigurability, this amplifier employs variable-bias active shunt feedback input matching, with a switchable capacitive load and a Q-enhancing negative gm circuit in parallel with the load. This design also features a noise cancelling technique, which helps to eliminate noise contributions from the primary gain FETs and simultaneously enhance the gain. This design was built on IBM's CMOS 0.13μm process through MOSIS and was designed for a 1.2V supply. This LNA has a min-to-max 3dB bandwidth ratio of approximately 3.1 while achieving a noise figure as low as 2.5dB, less than -10dB return loss, and IIP3 as high as -0.9dBm at low gain.