A 280-GHz Digitally Controlled Four Port Chip-Scale Dielectric Resonator Antenna Transmitter With DiCAD True Time Delay

A 280-GHz, fully integrated and digitally controlled multiport coherent radiator is presented. The silicon die acts as a chip-scale dielectric resonator antenna (CSDRA) and is excited by four differential loop inductors. The chip incorporates a balun for an X-band input signal, a 1-4 ultracompact differential Wilkinson splitter, and four ×27 active multipliers chain (AMC), which drive the four exciting elements. Highresolution, digitally controlled true time delay (TTD) elements, based on digitally controlled artificial dielectric transmission lines (DiCAD), are used to calibrate the variations between channels to optimize overall broadside radiated power and enable beam steering of ±15°. High-resolution DACs are used to accurately set the bias through a 3-wire SPI module. Fabricated in 65-nm CMOS, the 1.4×2-mm² chip achieves a record EIRP of +21 dBm, a TRP of +8.5 dBm, and a power density of 2.25 mW/mm² with 0.72% total efficiency, without using any external lens, superstrate, or postprocessing.