A 15-50 GHz LNA With 2.4 dB NF and 25.4±1.4 dB Gain In 0.15 um GaAs pHEMT Process

A four-stage ultra-wideband $15-50 \mathrm{GHz}$ LNA in 0.15 um GaAs pHEMT process is presented in this paper. A RLC feedback with a virtual ground capacitance (RLC&VGC) topology used in current-reuse structure is proposed, which enables flexible adjustment of both low- and high-frequency gain. Moreover, a RC parallel circuit and LR series circuit are exploited to improve gain flatness. Several bandwidth extension techniques are employed to expand the bandwidth up to 50 GHz. A prototype of a four-stage common-source (CS) LNA with the proposed techniques is designed and fabricated in a 0.15 um GaAs pHEMT process. Measurement results show a noise figure (NF) of 2.4 dB, a gain exceed 24 dB with the gain flatness of ±1.4 dB. Due to the utilization of the self-biasing technology, the chip consumes a DC power of 168 mW with a single DC supply of +4 V. The amplifier achieves good linearity, with an output 1 dB compression point ($\mathrm{OP}_{1 \mathrm{~dB}}$) of 13.4 dBm and a third-order intercept point (OIP3) of $\mathbf{2 3} \mathbf{~ d B m}$.