부산대학교 도서관

Massive MIMO or digital-beamforming transceiver systems, shown in Fig. 19.7.1, offer flexibility for multiband, multi-user, and joint communication-and-sensing platforms. However, wideband MIMO applications increase the number of desired or interfering signals that impinge on each channel, creating higher input-power-compression $(\mathrm{P}_{1\text{dB}})$ or 3rd-order input-intercept-point (IIP3) linearity requirements in both the transmitting and receiving RF paths. In high-performance commercial and defense radios, CMOS mixers place critical limitations on receiver linearity as the LNA output typically compresses the mixer, leading to recent work on mixer-first approaches in CMOS to improve receiver linearity [1]. When highly linear microwave mixers are demanded, IIIV processes, such as GaAs, are favored for Schottky diodes, which offer lower $\mathrm{R}_{\text{on}}\mathrm{C}_{\text{off}}$ and high barrier voltages. Commercially available GaAs mixers offer IIP3s exceeding 30dBm. However, III-V mixers typically use a separate process for the driver amplifier, resulting in multiple chips with high driver power consumption (typically exceeding 1W) to deliver the required 15-to-30dBm LO power across a broad LO frequency range [2].