An 8 × 8 MIMO Radar System Utilizing Cascadable Transceiver MMICs With On-Chip Antennas at 240 GHz

This article introduces a 240-GHz multiple-input-multiple-output (MIMO) radar chipset, consisting of a 120-GHz voltage-controlled oscillator (VCO) monolithic microwave integrated circuit (MMIC) for generating the local oscillator (LO) signal and a 240-GHz transceiver (TRX) MMIC, doubling the frequency and containing one transmitter (Tx) and one receiver (Rx) channel. The Tx channel has a digital vector modulator (VM), allowing for phase adjustments. The 120-GHz VCO has a tuning range of 27.2 GHz (23.6%). The MIMO frequency-modulated continuous-wave (FMCW) system capabilities are demonstrated using a phase-locked loop (PLL)-based VCO stabilization generating wideband, 30-GHz FMCW chirps, which are radiated using a time-division multiplexing (TDM) technique. The MMICs feature a cascadable approach, enabling the scalability of the array size by placing multiple TRX MMICs close to each other using a daisy chain approach. Furthermore, a circular polarized on-chip antenna allows rotation of the MMICs, and the TRX MMIC can be connected to two adjacent edges of the VCO MMIC, creating a 2D array for detecting targets in 3-D space. In the demonstrator setup using eight MMICs, the eight Tx channels of the MMICs generate an equivalent isotropically radiated power (EIRP) of 0 dBm each, reflected from the target and received by eight Rx channels. Overall, the demonstrator system contains 64 virtual elements integrated on an array size of less than $10 \times 10~\text {mm}^{2}$ .