A 64-Pixel 0.42 THz Source SoC with Spatial Modulation Diversity for Computational Imaging
This paper presents a terahertz source system-on-a-chip (SoC) specifically designed for computational imaging with a single pixel camera (SPC). The SoC consists of an 8×8 array of independent, frequency unlocked THz sources that together radiate maximum 10.3 dBm power at 0.42 THz. Each source pixel is composed of a fundamental Colpitts oscillator, followed by a common-collector doubler, and an on-chip circular slot antenna. The THz power radiated from the array can be modulated in space by turning the pixels on or off individually with 100% modulation depth. The SoC integrates a dedicated memory space where 64 of such spatial patterns can be stored and triggered externally at up to 10 MHz modulation rate. The spatial modulation can be additionally multiplexed with separate programmable chopping rates for individual pixels. The combined modulation diversity provides a highly reconfigurable THz light projection for SPCs. Furthermore, each pixel also incorporates a built-in power-test (BIST) for an in-situ radiation power monitoring and calibration. All of the aforementioned functions are programmable with an integrated ASIC through a standard SPI interface. This integration level readily allows low-cost aperture scaling by combining multiple chips at the board level. The SoC was applied in a compact, 8×8 pixel, silicon-only THz SPC which captures transmission mode images at 25 frames per second with 40 dB voltage dynamic range. With an appropriate receiver and baseband processing, the imaging speed of such SPCs can be extended to thousands of frames per second.
This document is the accepted manuscript version that has been published in final form in: IEEE Journal of Solid-State Circuits. https://doi.org/10.1109/JSSC.2020.3018819
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