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이재성(Jae-Sung Rieh) 한국전자파학회 2021 한국전자파학회논문지 Vol.32 No.6
테라헤르츠 신호원은 최근 관심이 증가하는 테라헤르츠 시스템의 구현에 있어서 핵심적인 요소이다. 테라헤르츠 신호원은 광소자 기반 혹은 전자소자 기반으로 구현이 가능하며, 전자소자 기반은 다시 진공소자 기반과 고체소자 기반으로 나누어 볼 수 있다. 본 논문은 고체소자 기반 신호원의 일반적인 형태인 반도체 전자소자 기반 테라헤르츠 신호원에 대한 개요를 제공하는 목적을 가지고 작성되었다. 먼저 다이오드 기반 테라헤르츠 신호원으로서 Gunn 다이오드, IMPATT 다이오드, RTD의 동작 원리 및 최근 보고된 성능을 기술하고, 이어서 트랜지스터 회로 기반 테라헤르츠 신호원으로서 LC cross-coupled 발진기, 콜피츠(Colpitts) 발진기, 링(ring) 발진기에 대해 그 동작 원리와 보고된 특성을 살펴본다. 이어 트랜지스터 회로 기반 테라헤르츠 신호원의 예로서 여러 가지 구조의 300 GHz 및 600 GHz 신호원을 소개하고, 그 특성을 기술한다. Terahertz (THz) signal sources are important elements that are used in THz systems and have been gaining interest in recent times. THz signal sources can be realized using either optical devices or electronic devices. The latter approach can be divided into signal sources based on vacuum devices and solid-state devices. This paper provides an overview of THz sources that use semiconductor electronic devices, which are a typical kind of the solid-state devices. First, the operational principles and recent performance trends of diode-based THz signal sources, such as Gunn diodes, impact ionization avalanche transit-time (IMPATT) diodes, and resonant tunneling diodes (RTDs), are provided. Next, three types of transistor circuit-based THz signal sources, namely, LC cross-coupled oscillators, Colpitts oscillators, and ring oscillators, are described according to their topologies and performance. Finally, various types of 300 GHz and 600 GHz oscillators are introduced as representative examples of transistor circuit-based signal sources.
Yongho Oh,Jae-Sung Rieh IEEE 2011 IEEE transactions on microwave theory and techniqu Vol.59 No.6
<P>This paper presents a comprehensive study on the high-Q island-gate varactor (IGV), which includes a comparison with the conventional multifinger varactors (MFVs) and analyses on the effect of structural variations on the varactor performance. The study shows that the IGV exhibits smaller R(s) and larger Q factor compared to the MFV, while its capacitance tuning ratio is smaller. The effect of the dimension variation and shape of the gate island, as well as the gate thickness, is substantial and the observed trends can be exploited for IGV optimization. This work indicates that the IGV is a highly promising option for millimeter-wave applications.</P>
Jeongkyu Heo,Jae Choon Kim,Ki Hyuk Kim,Jae-Sung Rieh,Jin Taek Chung,Sung Woo Hwang IEEE 2008 IEEE microwave and wireless components letters Vol.18 No.5
<P>We fabricated and characterized heterojunction field effect transistor radio frequency (RF) power amplifier (PA) test fixtures, for wireless applications, with various printed circuit board (PCB) structures. The RF matching and bias circuits of the test fixtures were designed so that they had the same RF characteristics. The only source of the variation of the RF gain (S<SUB>21</SUB>) was different thermal characteristics of each PCB. The values of the junction temperature (T<SUB>J</SUB>) and the junction-to-ambient thermal resistance (R <SUB>J</SUB> <SUB>A</SUB>) of each test fixture were shown to be changed as much as 80deg C and 30deg C / W, respectively, by the change of PCB structures. The change of Rja was shown to be originated from the change of the PCB thermal resistance, assuring that the structure of the PCB was the dominant factor in determining R <SUB>J</SUB> <SUB>A</SUB> Finally, we obtained a universal relation between S<SUB>21</SUB> of the amplifier and Tj. This work suggests that thermal budget of PCB is as important as that of package in wireless RF equipments.</P>
Effect of Device Layout on the Stability of RF MOSFETs
Yongho Oh,Jae-Sung Rieh IEEE 2013 IEEE transactions on microwave theory and techniqu Vol.61 No.5
<P>In this paper, the stability of RF MOSFETs is investigated in terms of the stability-factor (<I>k</I> -factor) for various layout schemes and device dimensions based on two different RFCMOS technologies. To systematically analyze the effect of small-signal device model parameters on RF MOSFET stability, the expression for <I>k</I>-factor is derived as a function of the small-signal model parameters of RF MOSFETs. Based on the expression, the effect of small-signal model parameters on the stability of RF MOSFETs is explored along with its bias dependence. In addition, the effect of wiring schemes, number of gate fingers, gate finger pitch, and gate length is examined based on various device structures. It is shown that the transconductance and capacitances are the dominant device parameters to determine the stability of RF MOSFETs. The result also indicates that the stability of RF MOSFETs is strongly affected by the details of layout scheme and lateral dimension. Additionally, it was found that there is a tradeoff between device stability and speed. This study is expected to serve a guideline for the device design and optimization for stable operation of RF MOSFETs and circuits based on them.</P>
A Low Power V-Band Injection-Locked Frequency Divider in 0.13-µm Si RFCMOS Technology
SEO, Seungwoo,RIEH, Jae-Sung The Institute of Electronics, Information and Comm 2010 IEICE transactions on electronics Vol.93 No.5
<P>In this work, a divide-by-2 injection locked frequency divider (ILFD) operating in the V-band with a low DC power consumption has been developed in a commercial 0.13-µm Si RFCMOS technology. The bias current path was separated from the injection signal path, which enabled a small supply voltage of 0.5V, leading to a DC power consumption of only 0.31mW. To the authors' best knowledge, this is the lowest power consumption reported for mm-wave ILFDs at the point of writing. All inductors and interconnection lines were designed based on EM (electromagnetic) simulator for precise prediction of circuit performance. With varactor tuning voltage ranged for 0-1.2V, the free-running oscillation frequency varied from 27.43 to 28.06GHz. At 0dBm input power, the frequency divider exhibited a locking range of 5.8GHz from 53 to 58.8GHz without external tuning mechanism. The fabricated circuit size is 0.72mm × 0.62mm including the RF and DC supply pads.</P>
CMOS 120 GHz Phase-Locked Loops Based on Two Different VCO Topologies
Junghwan Yoo,Jae-Sung Rieh 한국전자파학회JEES 2017 Journal of Electromagnetic Engineering and Science Vol.17 No.2
This work describes the development and comparison of two phase-locked loops (PLLs) based on a 65-nm CMOS technology. The PLLs incorporate two different topologies for the output voltage-controlled oscillator (VCO): LC cross-coupled and differential Colpitts. The measured locking ranges of the LC cross-coupled VCO-based phase-locked loop (PLL1) and the Colpitts VCO-based phase-locked loop (PLL2) are 119.84−122.61 GHz and 126.53−129.29 GHz, respectively. Th e output powers of PLL1 and PLL2 are −8.6 dBm and −10.5 dBm with DC power consumptions of 127.3 mW and 142.8 mW, respectively. The measured phase noise of PLL1 is −59.2 at 10 kHz offset and −104.5 at 10 MHz offset, and the phase noise of PLL2 is −60.9 dBc/Hz at 10 kHz offset and −104.4 dBc/Hz at 10 MHz offset. The chip sizes are 1,080 μm × 760 μm (PLL1) and 1,100 μm × 800 μm (PLL2), including the probing pads.
Daekeun Yoon,Jongwon Yun,Jae-Sung Rieh IEEE 2015 IEEE transactions on terahertz science and technol Vol.5 No.4
<P>A THz voltage-controlled oscillator (VCO) has been developed in this work based on a 0.25-mu m InP heterojunction bipolar transistor (HBT) technology. The cross-coupled push-push oscillator adopted a novel coupled-line topology, in which the DC blocking capacitors and the load inductance are replaced by a pair of coupled-lines to improve the oscillation frequency and reduce the circuit area. Also, a base bias tuning was employed for effective oscillation frequency tuning. The circuit exhibited the voltage tuning from 309.5 GHz to 339.5 GHz, leading to a tuning range of 30 GHz. The maximum output power was -6.5 dBm at 334 GHz, achieved with a dc power consumption of 13.5 mW. Measured phase noise was -86.55 at 10-MHz offset. The circuit occupies only 0.014 mm(2) excluding the probing pads.</P>