A Fully Integrated Modular 2×4 220–260 GHz Beam-Forming Transmitter and Receiver With 50 Gbps Wireless Transmission in SiGe:C BiCMOS

This article presents a 220–260 GHz fully integrated phased-array wireless system featuring direct conversion RF beam-forming. The system is constructed using fully integrated transmitter (Tx) and receiver (Rx) chips with on-chip antenna array. A four-channel Tx and Rx are designed and fabricated in a 130-nm SiGe BiCMOS process with f$_{\mathbf{T}}$/f$_{\mathbf{max}}$ = 300/500 GHz. A modular design approach enables the chips as building units for 2×N phased arrays and multiple-input multiple-output systems. A comprehensive design approach for the Tx and Rx chips focusing on key design decisions is presented in this work. The transmitter is equipped with a local oscillator (LO) multiplication chain, IQ up $-$ conversion mixer, active RF splitting network, vector modulator phase shifter (VMPS), temperature sensors, and high output power amplifiers (PA). The PA with power $-$ combining boost the effective isotropic radiated power (EIRP) and reduces the need for external lenses. The receiver is equipped with an LO chain, IQ down $-$ conversion mixer, active RF combining network, VMPS, and low noise amplifiers (LNA). In both Tx and Rx the antenna array is composed of four differential double-folded dipole antennas with local backside etching. The Tx and Rx chips consume 4.4 W and 1.84 W of power, respectively, from a 3.5 V supply with each occupying 25 mm$^{\text{2}}$ of silicon area. With a measured Tx array EIRP of 24 dBm, a beamforming wireless link is demonstrated supporting up to 50 Gbps of data rates across 85 cm of link distance with no need for focusing lenses and $\pm 30^\circ$ of scanning capability. With these capabilities, the presented modular chips enable future scaling for 2× N antenna arrays for sensing and communication applications.