A dual-band LNA with active balun for GNSS receivers

This paper presents the design and implementation of a dual-band reconfigurable low noise amplifier (LNA) for multi-band GNSS receivers. The proposed LNA incorporates an active balanced-to-unbalanced (balun) conversion and a step gain control. The LNA also utilizes a constant g
_m
biasing to maintain a constant LNA gain over process, voltage, temperature (PVT) variations. The operating frequency of the LNA can be configured at either 1.2GHz or 1.57GHz by off-chip matching network. The LNA is designed in a 0.18-μm CMOS process, occupying a die area of 0.65 × 0.55mm
²
, including ESD, power clamp and bonding pads. Post-simulation results show that the proposed dual-band LNA achieves a voltage gain of 25dB and 22dB, a noise figure (NF) of 2.1dB and 2.3dB, at 1.2GHz and 1.57GHz respectively. The LNA draws 3.5mA current from a 1.8V supply.