288-GHz CMOS Source Radiates -4.1 dBm

At 300 GHz and beyond, room-temperature imaging detectors—and incoherent direct detectors in particular—lack the sensitivity of a low-noise amplifier (LNA). As a result, only active imaging approaches provide the needed signal-to-noise ratio (SNR). This issue has underscored the need for robust, lightweight, and low-cost power sources in the sub-millimeter-wave range. Above 200 GHz, however, the output power of both electronic and photonic signal sources rapidly drops. At Germany’s University of Wuppertal, a 288-GHz lens-integrated, high-power source has been implemented in 65-nm CMOS by Janusz Grzyb, Yan Zhao, and Ullrich Pfeiffer.

Two free-running triple-push ring oscillators, which are locked out of phase by magnetic coupling, comprise the engineers’ source. The oscillators drive a differential on-chip ring antenna. That antenna, in turn, illuminates a hyper-hemispherical silicon lens through the die’s backside. An on-wafer breakout of the oscillators’ core achieves peak output power of -1.5 dBm with 275-mW direct-current (DC) power consumption. The packaged source delivers -4.1 dBm of radiated power. The source measures just 500 x 570 μm² including the antenna. See “A 288-GHz Lens-Integrated Balanced Triple-Push Source in a 65-nm CMOS Technology,” IEEE Journal Of Solid-State Circuits, July 2013, p. 1751.