Browsing by Author "Song, Kiryong"

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Approaches to Enhance the Performance of SiGe Imagers Operating near 130 GHz and 300 GHz
(2016)
Rieh, Jae-Sung
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Yoon, Daekeun
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Yun, Jongwon
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Song, Kiryong
;
Kim, Jungsoo
A comparison is made on high-frequency SiGe imagers to investigate the performance enhancement with circuit-level approaches: employing a front-end low noise amplifier (LNA) and employing heterodyne topology. Two imagers operating near 130 GHz, one with and the other without an LNA, were compared for the responsivity and the noise equivalent power (NEP). Also, two imagers operating near 300 GHz, one in direct and the other in heterodyne topology, were compared for the same parameters. Inserting a front-end LNA has led to changes in the peak responsivity and the minimum NEP with a factor of 63.5 and 0.011, respectively, near 130 GHz. Employing heterodyne topology for the 300 GHz imager resulted in changes with a factor of 52.8 and 0.18 for the same parameters.
Terahertz Reflection-Mode Biological Imaging Based on InP HBT Source and Detector
(2017-05-01)
Yun, Jongwon
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Oh, Seung Jae
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Song, Kiryong
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Yoon, Daekeun
;
Son, Hye Young
This paper presents the development of an oscillator and a detector based on InP HBT technology operating near 300 GHz, and their application to terahertz reflection-mode imaging. The fabricated fundamental-mode common-base (CB) cross-coupled oscillator exhibits a peak output power of 5.3 dBm at 305.8 GHz, and the CB direct detector shows a responsivity higher than 40 kV/W and noise equivalent power lower than 35 pW/root Hz for a frequency range of 270-345 GHz. The imaging system employing the fabricated circuits as the signal source and detector was characterized for the resolution and dynamic range, and then, successfully applied for imaging various biological samples. The results show that low-power terahertz reflection-mode imaging based on solid-state electronic sources and detectors based on a commercial semiconductor technology is promising for various biomedical imaging applications.
Three-Dimensional Terahertz Tomography With Transistor-Based Signal Source and Detector Circuits Operating Near 300 GHz
(2018-09-01)
Kim, Jungsoo
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Yoon, Daekeun
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Yun, Jongwon
;
Song, Kiryong
;
Kaynak, Mehmet
In this paper, three-dimensional (3-D) terahertz (THz) tomography was demonstrated with a signal source and imagers based on transistor circuits fabricated with standard semiconductor technologies. For the signal source, a 300-GHz oscillator based on InP HBT technology was employed. For detection, two types of imagers operating near 300 GHz were employed, one direct and the other heterodyne, both realized with SiGe HBT technology. With a set of 2-D images taken from different angles, sinograms and tomograms were obtained, which led to a successful reconstruction of 3-D images of the target object based on the filtered back-projection algorithm. A systematic comparison was made for the direct imager and the heterodyne imager, for which the signal input power and the video bandwidth were varied for both imagers. The results revealed that the heterodyne imager shows a better sensitivity than the direct imager. However, a similar dynamic range of around 30 dB was achieved for both imagers because of a saturation observed for the heterodyne imager when the input power exceeds the threshold. The video bandwidth did not affect the image quality significantly for the bandwidth variation over four orders of magnitude for both imagers.