• 한국광학회:학술대회논문집
• /
• 한국광학회 1999년도 제16회 광학 및 양자전자 학술발표회Proceedings of 16th Optics and Quantum Electronics Conference, 1999
• /
• pp.224-225
• /
• 1999

• 한국광학회:학술대회논문집
• /
• 한국광학회 2004년도 제15회 정기총회 및 동계학술발표회
• /
• pp.94-95
• /
• 2004

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제16권1호
• /
• pp.31-38
• /
• 2016

A novel self-reference sense amplifier with parallel reading during writing operation is proposed. Read access time is improved compared to conventional self-reference scheme with fast operation speed by reducing operation steps to 1 for read operation cycle using parallel reading scheme, while large sense margin competitive to conventional destructive scheme is obtained by using self-reference scheme. The simulation was performed using standard $0.18{\mu}m$ CMOS process. The proposed self-reference sense amplifier improved not only the operation speed of less than 20 ns which is comparable to non-destructive sense amplifier, but also sense margin over 150 mV which is larger than conventional sensing schemes. The proposed scheme is expected to be very helpful for engineers for developing MRAM technology.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제3권1호
• /
• pp.42-46
• /
• 2003

In this paper, an MMIC broadband amplifier for wireless communication systems has been developed by using an active feedback method. This active feedback operates at much higher frequencies than a method by a spiral inductor feedback and its size is independent of the inductance value. The MMIC broadband amplifier was designed using a $0.5{\;}{\mutextrm{m}}$ MESFET library. The fabricated chip area was $1.4{\;}mm{\;}{\times}{\;}1.4{\;}mm. Measurement showed a gain of 18 dB with a gain flatness of ${\pm}3$ dB in a 1.5 GHz~3.5 GHz band. The maximum output power and the minimum noise figure were 14 dBm and 2.5 dB in the same band, respectively.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제8권2호
• /
• pp.128-133
• /
• 2008

Phase-change random access memory (PRAM) chip cell phase of amorphous state is rapidly changed to crystal state above 160 Celsius degree within several seconds during Infrared (IR) reflow. Thus, on-board programming method is considered for PRAM chip programming. We demonstrated the functional 512Mb PRAM with 90nm technology using several novel core circuits, such as metal-2 line based global row decoding scheme, PN-diode cells based BL discharge (BLDIS) scheme, and PMOS switch based column decoding scheme. The reverse-state standby current of each PRAM cell is near 10 pA range. The total leak current of 512Mb PRAM chip in standby mode on discharging state can be more than 5 mA. Thus in the proposed BLDIS control, all bitlines (BLs) are in floating state in standby mode, then in active mode, the activated BLs are discharged to low level in the early timing of the active period by the short pulse BLDIS control timing operation. In the conventional sense amplifier, the simultaneous switching activation timing operation invokes the large coupling noise between the VSAREF node and the inner amplification nodes of the sense amplifiers. The coupling noise at VSAREF degrades the sensing voltage margin of the conventional sense amplifier. The merit of the proposed sense amplifier is almost removing the coupling noise at VSAREF from sharing with other sense amplifiers.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제2권2호
• /
• pp.125-131
• /
• 2002

This paper presents MMIC drive and power amplifiers covering 6-18 ㎓. For simple wideband impedance matching and less sensitivity to fabrication variation, modified distributed topologies are employed in the both amplifiers. Cascade amplifiers with a self-biasing circuit through feedback resistors are used as unit gain blocks in the drive amplifier, resulting in high gain, high stability, and compact chip size. Self impedance matching and high-pass, low-pass impedance matching networks are used in the power amplifier. In measured results, the drive amplifier showed good return losses ($S_11,{\;}S_{22}{\;}<{\;}-10.5{\;}dB$), gain flatness ($S_{21}={\;}16{\;}{\pm}0.6{\;}dB$), and $P_{1dB}{\;}>{\;}22{\;}dBm$ over 6-18 GHz. The power amplifier showed $P_{1dB}{\;}>{\;}28.8{\;}dBm$ and $P_{sat}{\;}{\approx}{\;}30.0{\;}dBm$ with good small signal characteristics ($S_{11}<-10{\;}dB,{\;}S_{22}{\;}<{\;}-6{\;}dB,{\;}and{\;}S_{21}={\;}18.5{\;}{\pm}{\;}1.25{\;}dB$) over 6-18 GHz.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제14권2호
• /
• pp.235-245
• /
• 2014

This paper presents an envelope tracking power amplifier using a standard CMOS process for the 3GPP long-term evolution transmitters. An efficiency of the CMOS power amplifier for the modulated signals can be improved using a highly efficient and wideband CMOS bias modulator. The CMOS PA is based on a two-stage differential common-source structure for high gain and large voltage swing. The bias modulator is based on a hybrid buck converter which consists of a linear stage and a switching stage. The dynamic load condition according to the envelope signal level is taken into account for the bias modulator design. By applying the bias modulator to the power amplifier, an overall efficiency of 41.7 % was achieved at an output power of 24 dBm using the 16-QAM uplink LTE signal. It is 5.3 % points higher than that of the power amplifier alone at the same output power and linearity.

• 한국정보통신학회논문지
• /
• 제18권11호
• /
• pp.2697-2702
• /
• 2014

본 논문에서는 위성 통신 시스템 응용을 위하여 Ku 대역에서 동작 가능한 2W MMIC (monolithic microwave integrated circuit) 전력증폭기를 개발하였다. 2W MMIC 전력증폭기는 WIN (wireless information networking) semiconductor Corp.의 GaAs 기반 PHEMT (pseudomorphic high electron mobility transistor) 공정을 사용하여 개발되었다. 개발된 Ku 대역 2W MMIC 전력증폭기의 측정결과, 13.75 GHz ~ 14.5 GHz의 동작주파수 범위에서 29 dB 이상의 이득, 33.4 dBm 이상의 포화 출력전력을 얻었다. 특히 전력부가효율은 29 %로 기존에 발표된 GaAs 기반 Ku 대역 2W MMIC 전력증폭기 상용 제품들에 비하여 높은 결과를 얻을 수 있었다.

• 전기전자학회논문지
• /
• 제24권4호
• /
• pp.1093-1097
• /
• 2020

본 논문에서는 위성 통신 시스템 응용을 위하여 Ku-대역에서 동작하는 3 W PHEMT MMIC 전력 증폭기의 특성을 기술한다. 3 W PHEMT MMIC 전력 증폭기는 WIN(wireless information networking) semiconductor Corp.에서 제공하는 게이트 길이가 0.25 ㎛인 GaAs 기반 PHEMT (pseudomorphic high electron mobility transistor) 공정을 사용하여 개발되었다. 개발된 Ku-대역 PHEMT MMIC 전력 증폭기는 13.75 GHz에서부터 14.5 GHz까지의 동작주파수 범위에서 22.2~23.1 dB의 소신호 이득과 34.8~35.4 dBm의 포화 출력 전력을 가진다. 최대 포화 출력 전력은 13.75 GHz에서 35.4 dBm (3.47 W)이었다. 전력 부가 효율은 30.8~37.83%의 특성을 얻었으며 칩의 크기는 4.4 mm×1.9 mm이다. 개발된 PHEMT MMIC 전력 증폭기는 다양한 Ku-대역 위성 통신 시스템 응용에 적용 가능할 것으로 예상된다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 디스플레이 광소자 분야
• /
• pp.197-200
• /
• 2000

All-optical NOR logic device was realized by use of two pump signals with a single wavelength and a semiconductor optical amplifier(SOA). Specially, Mach-Zehnder(MZ) modulator was used for an external modulation of the pump signals. To obtain the sufficient gain saturation of the SOA, pump signals are amplified by an Er-doped fiber amplifier(EDFA) at the input of the SOA. Pump and probe signals are obtained from a DFB laser diode(${\lambda}_p$=1554 nm) and a tunable laser diode(${\lambda}_s$=1535 nm), respectively. The operation characteristics of the NOR logic device are successfully measured and demonstrated at the modulation frequency of 4.83 MHz.