LAUSR

This article presents a 140-GHz eight-element wafer-scale phased-array transmitter based on intermediate-frequency (IF) beamforming with 5-bit phase and 4-bit gain control in the GlobalFoundries 45RFSOI process. The chip contains a shared local-oscillator (LO) multiplier chain and distribution network for a phased-array transmitter system solution. Image rejection filters are designed before the RF front-end power amplifiers (PAs) to suppress the image and improve the PA linearity. A differential on-chip antenna feed is electromagnetically coupled to a high-efficiency microstrip antenna on a 100- $\mu \text{m}$ -thick quartz superstrate, and the antennas are placed $\lambda $ /2 (~140 GHz) apart in the horizontal and vertical directions. The $4\times 2$ element phased-array chip with attached quartz superstrate is wirebonded to a printed circuit board containing IF and LO ports and scans to ±30° in the elevation plane ( $E$ -plane). The measured array peak electronic gain is 21 dB with an RF 3-dB bandwidth of 136–147 GHz and an IF bandwidth of 3–4 GHz. The measured array peak effective isotropic radiated power (EIRP) is 30–32 dBm at 134–142 GHz. To evaluate the over-the-air (OTA) performance, a transmit (Tx) array-horn communication link is demonstrated with quadrature phase shift keying (QPSK), 16-quadrature amplitude modulation (QAM), and 64-QAM waveforms, supporting up to 16–18-Gb/s data rates. Also, a transmit–receive phased-array wireless link at 0.65 m is demonstrated with 11–12-Gb/s data rates using 16- and 64-QAM waveforms. To the best of our knowledge, this article presents the first CMOS wafer-scale phased-array transmitter at 140 GHz with high EIRP and data rate.