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 - Funding Information:
The authors would like to thank Office of Naval Research (YIP), Air Force Office of Scientific Research (MURI), and National Science Foundation for funding support. We would also like to greatly thank Prof. Omeed Momeni at U.C. Davis for lending the detector measurement setup.
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.
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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 -