Two 7–13-GHz GaAs-SiGe Four–Channel Beamforming Chiplets With/Without Metallic Interlayer Shields

This paper presents two 7-13 GHz GaAs-SiGe four-channel beamforming chiplets to minimize the chip area. The chips integrate GaAs-based power amplifiers (PAs) and low-noise amplifiers (LNAs) with silicon-based phase and amplitude control modules using gold bumps. To mitigate coupling between the metal patterns of the heterogeneous chips and avoid interference with beamforming performance, a metallic interlayer shield is introduced at the interface. This shield ensures effective integration and preserves the functionality and performance of both the compound and silicon-based components. The fabricated 4-channel 3D heterogeneous integrated RF front-end chips, using 0.25-μm GaAs and 0.13-μm SiGe BiCMOS processes, achieve 6-bit amplitude/phase control with 0.5 dB/5.625resolution with power consumption of 3.6 W (TX) and 1.6 W (RX). The RMS amplitude and phase errors are <0.6 dB and <2.5, respectively, outperforming the version without the interlayer shield (1.0 dB/2.8). The proposed transceiver achieves a 19-dBm TX OP1dB and -1.5-dBm RX IP1dB, with a compact total area of 4.1 × 3.05 mm2.