A 2X2 0.232-0.243 THz coherent scalable array in 28nm CMOS

In this paper, we present a novel method to scale coherent single sources/lD arrays into 2D arrays without the use of lossy power divider signal distribution. In our proposed method, we use the leaked fundamental from a non-linear harmonic generator circuit as an input to drive the next element in the chain. A 232-243 GHz radiating 2×2 array is designed in 28nm CMOS to demonstrate this method. A single transmitter (Tx) element consists of a 75-83 GHz driving stage, 75-83 GHz PA (power amplifier) followed by a frequency tripler to 225-240 GHz. The fundamental 75-83 GHz signal leaked from the frequency tripler is coupled using a balun and used to drive the next Tx element. The third harmonic current from the frequency tripler is coupled using the balun and delivered to the antenna element which is matched to third harmonic. The antenna elements excite the silicon die itself which radiates as a dielectric resonance antenna (DRA). Biasing control is used to tune the phase at the fundamental harmonic thus tripling phase shift at the third harmonic between antenna elements. The lens-less radiating array achieves a measured directivity of 9. 5dBi with 60% efficiency. The 2×2 Tx array achieves a peak EIRP of 18dBm with peak radiated power of 8dBm at 1.2% RF/DC efficiency and demonstrated 2D beam steering.