14.5 A 0.53THz reconfigurable source array with up to 1mW radiated power for terahertz imaging applications in 0.13μm SiGe BiCMOS

Abstract

Recently, silicon-based THz video cameras have been demonstrated for industrial, surveillance, scientific, and medical applications in the THz range (300GHz to 3THz) [1]. Such camera implementations favor pixels with antennacoupled direct detectors for a low power dissipation and a high pixel count. Despite this progress, they lack the required sensitivity for passive imaging and imagers are in the need of artificial illumination to provide the required image quality. The choice has been to use expensive high-power focused illumination with a single direction for the incoming beam, which seriously limits the image quality due to its specular nature. Additionally, detectors in a focal-plane array configuration share the available source power and the image SNR further drops with the camera resolution. Like imaging at visible light, where shades or reflectors are commonly used, active THz imaging would greatly benefit from incoherent artificial light sources to adjust brightness, phase/frequency, and the direction of light to obtain the desired lighting conditions.

A SiGe Terahertz Heterodyne Imaging Transmitter With 3.3 mW Radiated Power and Fully-Integrated Phase-Locked Loop

“…Unfortunately, conventional push-push oscillators [10]do not meet such optimum conditions, and therefore lead to smaller oscillation power. Triple-push topology ( [11], [16], [22]) can achieve the optimum phase, but the 3rd-order harmonic generation is normally less efficient than the 2nd-order harmonic generation. Meanwhile, due to the ring topology, it is difficult to connect the oscillator output to an on-chip antenna, which is big in size .…”

“…Besides these work in CMOS, radiation sources in BiCMOS processes also demonstrate great potential, thanks to the superior speed and breakdown voltage of the SiGe heterojunction bipolar transistor (HBT) [14]. For example, radiators using a 130 nm SiGe BiCMOS process ( GHz, V) achieve 1.3 mW of power at 245 GHz [15]and 74 W (single element)/1 mW (incoherent array) of power at 530 GHz [16]. Fig.…”

On design of differentially driven on-chip antennas with harmonic filtering for silicon integrated mm-wave and THz N-push oscillators

“…The first at 284-288 GHz is implemented in a bulk 65-nm CMOS process (fmax of 200 GHz) and delivers a radiated output power of -4.1 dBm [10]. The other operating at 519-536 GHz is realized in a 0.13μm SiGe BiCMOS technology with peak ft/fmax of 300/500 GHz, delivering the highest radiated power of -11.3dBm (85μW) ever reported for silicon technologies beyond 500 GHz [11]. In order to address the above-mentioned idea of source configurability, the latter was additionally implemented in a 4x4 array arrangement with programmable diversity and a total radiated power of up to 1mW.…”

2.1 An integrated 0.56THz frequency synthesizer with 21GHz locking range and −74dBc/Hz phase noise at 1MHz offset in 65nm CMOS

“…It would be beneficial to further develop frequency synthesizers at the scientifically important 0.5-to-0.6THz in mainstream CMOS technologies with larger integration and lower power than that of SiGe HBT counterparts. Although VCOs/multipliers [3][4][5][6] have been developed at these frequencies, the realization of wide-bandwidth and low-phase-noise synthesizers remains challenging due to the following obstacles: (a) the use of varactors or other passives for frequency tuning radically lowers the tank quality and inhibits oscillation; (b) there is no proven injection-locked frequency divider (ILFD) that can operate beyond 0.2THz with a sufficiently wide frequency locking range. To date, no silicon based synthesizer has been reported beyond 0.32THz.…”

“…Spectra from 0.5 to 0.6THz play critical roles in planetary science, astrophysics and radio-astronomy as various chemical species including water, nitrates (NO 2 , N 2 O, NH 3 ) and organics (CH 4 and HCN) can either absorb or reflect radiation in this frequency regime. Accordingly, NASA and ESA have developed a wide range of spectroscopic sounding instruments to investigate our solar system.…”