A High Transmission Coefficient, Ultra-Low Noise and Wideband LNA for Use in Defence Applications

Abstract

The echo signal amplitude received by radar is very low, necessitating signal amplification for effective detection and processing. A Low Noise Amplifier (LNA) has been developed to boost signal amplitude without adding extra noise. This paper presents innovative techniques such as gm-boosting, RC coupling, an L-type matching network, and common source inductive degeneration. These techniques achieve a wide bandwidth of 1.3 GHz (4.7 to 6 GHz) and a low undesired signal level of 0.8 dB. The bias network enhances transconductance, resulting in a gain of 36-40 dB, while the RC coupling network ensures stability from DC to 36 GHz. The LNA achieves an output 1 dB compression point of 9 dBm, an OIP3 of 23.91 dBm, a sensitivity of -137.8 dBm, a linear dynamic range of 108.8 dB, and a spurious free dynamic range of 87.87 dB. This LNA operates well in RF interference environments and demonstrates strong detection capability and linearity. Built on GaAs technology, the MMIC circuit has a compact footprint of 3.5052 mm². This efficient LNA boosts the tracking range from 128 km to 243 km when integrated into larger systems.