Embracing the “Half-Wavelength” Challenge in Terahertz Regime: Radiator and Receiver 2D Arrays with Large Scale and High Density

In the RF regime, antennas are too big to be implemented on a chip. As the frequency extends into the mm-wave range, we can now comfortably integrate a few antennas, along with their associated electronics, in a single die. The situation becomes even more exciting when we push into the terahertz regime: an unprecedented number of antennas, operating with phase coherency, can be built in a chip, leading to large-scale power combining and ultra-narrow beamwidth. For example, a 3×3mm² chip area is expected to accommodate near 1000 radiators at 1THz and enable a beam with only a few degree of divergence. To do this, however, we need to embrace a critical challenge that, all building blocks of a unit, such as the antenna, signal source, frequency multiplier and filters, need to fit into a tiny lambda/2 by lambda/2 space, in order to suppress grating lobes. At 1THz and in the chip dielectric environment, that is only ~0.1mm×0.1mm ! Meanwhile, traditional centralized arrays also encounter excess loss and complexity hence fail to scale up. In this talk, we show our recent progress in addressing the above issues, by applying a tight integration of Si devices and multi-functional electromagnetism into new array architectures. Two mm²-sized prototypes, a 1THz SiGe source with 91 coherent radiators and a 0.24THz CMOS receiver with 32 phase-locked heterodyne units, will be presented.