A High-Power and Scalable 2-D Phased Array for Terahertz CMOS Integrated Systems

Abstract

This work introduces a 2-D phased array architecture that is suitable for high power radiation at mm-Wave and Terahertz frequencies. We address the challenge of signal generation above the cut-off frequency of transistors by presenting a radiation method based on the collective performance of a large number of synchronized sources. As theory shows, both frequency locking/ tuning and beam steering can be independently achieved by manipulating the local coupling between the nearest neighbors. This control method results in a dynamical network that is insensitive to array dimensions and is scalable to the point that can achieve a level of output power and spectral purity beyond the reach of conventional sources. To demonstrate the concept, we implement a 4 4 version of this phased array at 340 GHz using a 65 nm bulk CMOS process. The paper presents the design and implementation of the oscillators, couplings and the integrated antennas. The measured results at 338 GHz reveal a peak equivalent isotropically radiated power (EIRP) of +17.1 dBm and a phase noise of -93 dBc/Hz at the 1 MHz offset frequency. This chip presents the first fully integrated terahertz phased array on silicon. Furthermore, the output power is higher than any lens-less silicon-based source above 200 GHz and the phase noise is lower than all silicon radiating sources above 100 GHz.

Terahertz Beam Steering Technologies: From Phased Arrays to Field‐Programmable Metasurfaces

“…Adler's equations, which describe the relationship between the oscillator's locking frequency and the resultant phase difference between the resonant core and the input signal, provide another way to directly modulate the phase shift in the terahertz band: inject an external signal into the oscillator. Based on Adler's equations, a 338 GHz 2D phased array and a 240 GHz heterodyne receiver array consisting of 32 units were developed. Figure a shows the schematic of a 4 × 4 phased‐array network .…”

“…Based on Adler's equations, a 338 GHz 2D phased array and a 240 GHz heterodyne receiver array consisting of 32 units were developed. Figure a shows the schematic of a 4 × 4 phased‐array network . At the boundaries of the network, some auxiliary couplers are complemented to eliminate the mismatch, which is shown in Figure b.…”

“…c–f) Measured far‐field radiation patterns and beam steering for four different orientations ( Φ and Θ denote angles in two orthogonal directions). Reproduced with permission . Copyright 2015, IEEE.…”

Tutorial: Terahertz beamforming, from concepts to realizations

“…A more scalable approach to a frequency multiplieroriented terahertz phased array is to de-centralize the millimeter-wave feed network by coupling individual nodes to their neighbors rather than to a single millimeter-wave source. 133 Varactor-based phase shifters were employed in order to produce a relative phase shift between adjacent nodes, and this phase shift in the millimeter-wave signal translated to a corresponding phase shift in the radiated terahertz signal. Although the demonstrated device was of the same number of elements as in the previously discussed work (i.e., 4 × 4), it is more promising for the development of larger arrays.…”

Low-cost high-performance CMOS terahertz imaging system

“…A frequency multiplier chain is realizable [6], but usually consumes much dc power with low efficiency. If a harmonic oscillator is used, we have to tackle the issue of low output power by applying the technique such as optical power combining [7]. Nevertheless, those on-chip antennas not only exhibit low gain but also occupy large chip area.…”