A Fully-Integrated $S$-Band Differential LNA in $0.15-\mu \mathrm{m}$ GaAs pHEMT for Radio Astronomical Receiver

A fully-integrated S-band high-gain MMIC low noise amplifier (LNA) with differential input and single-ended output is presented and implemented in 0.15-μ m GaAs pHEMT for Square Kilometre Array (SKA) astronomical receiver. The low-loss input noise matching network is designed, and the fully on-chip LC balun is introduced between the first stage LNA core and the second stage amplifier to improve overall system noise figure. The 1-dB bandwidth of the LNA covers from 1.5 to 3.7 GHz. The measurement results demonstrate 31.8-dB gain, average in-band noise figure of 0.73 dB with DC power consumption of 25 mW. The chip area is 2.5 ×2 mm². Also, a noise figure measurement method for the 3-port differential-input-to-single-ended-output amplifiers is introduced in this paper.