TY - GEN
T1 - A 4×4 Distributed Multi-Layer Oscillator Network for Harmonic Injection and THz Beamforming with 14dBm EIRP at 416GHz in a Lensless 65nm CMOS IC
AU - Saeidi, Hooman
AU - Venkatesh, Suresh
AU - Chappidi, Chandrakanth Reddy
AU - Sharma, Tushar
AU - Zhu, Chengjie
AU - Sengupta, Kaushik
N1 - Publisher Copyright:
© 2020 IEEE.
PY - 2020/2
Y1 - 2020/2
N2 - Integrated high-power THz arrays with beamforming ability can enable new applications in communication, sensing, imaging, and spectroscopy [1]. However, due to the limited power-generation capability of a single source above the device fmax [2], efficient spatial power combining from multiple coherent sources becomes necessary to generate mW level of power. To create this 2D array of distributed frequency and phase-locked sources, prior works have shown central LO-signal distribution with local harmonic upconversion [3]. However, this requires high power consumption in the LO distribution. In addition, phase-matching with PVT variations across the sources at the harmonic-radiating THz frequency can be quite challenging. A small θ perturbation at the fundamental frequency translates to Nθ at the radiated Nth harmonic, thus corrupting the array beam pattern. Another method to synchronize multiple distributed radiating sources (/2 spaced at Nfo) is through a mutual coupling network with active/passive elements in a coupled oscillator array [4], [5]. However, the locking range in these methods is typically narrow (flocking f0/20 to f0/10) and PVT variations can easily cause desynchronization. In such a network, each cell is a self-sustaining oscillator, and the coupling network tries to establish injection signals to force synchronization between these individual free-running oscillators. In this paper, we used a 2D oscillating network with negative Gm(-Gm) cells at each node that do not oscillate individually but only collectively, establishing a robust frequency and phase distribution network across the chip for high THz-power generation. By making this network as the lowest layer, we can now separate the locking mechanism and the power-generation sources. This avoids loading and sub-optimal operation of the power sources. The distributed oscillating network at the lowest layer operates at 69.3GHz, and multi-layer local harmonic generation produces a radiated power of -3dBm and +14dBm EIRP at 416GHz in a 4×4 array.
AB - Integrated high-power THz arrays with beamforming ability can enable new applications in communication, sensing, imaging, and spectroscopy [1]. However, due to the limited power-generation capability of a single source above the device fmax [2], efficient spatial power combining from multiple coherent sources becomes necessary to generate mW level of power. To create this 2D array of distributed frequency and phase-locked sources, prior works have shown central LO-signal distribution with local harmonic upconversion [3]. However, this requires high power consumption in the LO distribution. In addition, phase-matching with PVT variations across the sources at the harmonic-radiating THz frequency can be quite challenging. A small θ perturbation at the fundamental frequency translates to Nθ at the radiated Nth harmonic, thus corrupting the array beam pattern. Another method to synchronize multiple distributed radiating sources (/2 spaced at Nfo) is through a mutual coupling network with active/passive elements in a coupled oscillator array [4], [5]. However, the locking range in these methods is typically narrow (flocking f0/20 to f0/10) and PVT variations can easily cause desynchronization. In such a network, each cell is a self-sustaining oscillator, and the coupling network tries to establish injection signals to force synchronization between these individual free-running oscillators. In this paper, we used a 2D oscillating network with negative Gm(-Gm) cells at each node that do not oscillate individually but only collectively, establishing a robust frequency and phase distribution network across the chip for high THz-power generation. By making this network as the lowest layer, we can now separate the locking mechanism and the power-generation sources. This avoids loading and sub-optimal operation of the power sources. The distributed oscillating network at the lowest layer operates at 69.3GHz, and multi-layer local harmonic generation produces a radiated power of -3dBm and +14dBm EIRP at 416GHz in a 4×4 array.
UR - http://www.scopus.com/inward/record.url?scp=85083856777&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85083856777&partnerID=8YFLogxK
U2 - 10.1109/ISSCC19947.2020.9063076
DO - 10.1109/ISSCC19947.2020.9063076
M3 - Conference contribution
AN - SCOPUS:85083856777
T3 - Digest of Technical Papers - IEEE International Solid-State Circuits Conference
SP - 456
EP - 458
BT - 2020 IEEE International Solid-State Circuits Conference, ISSCC 2020
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 2020 IEEE International Solid-State Circuits Conference, ISSCC 2020
Y2 - 16 February 2020 through 20 February 2020
ER -