• Proceedings of the IEEK Conference
• /
• 2000.11a
• /
• pp.381-384
• /
• 2000

In this paper, we designed and fabricated a low noise amplifier which can be used in W-CDMA. For improving input VSWR and stability an emitter inductance series feedback was used, and for acquiring higer linearity at low current DC bais by-passing method was used. Fabricated low noise amplifier had 15.33 ㏈ power gain, 2.17 ㏈ NF, -9.53 ㏈ $S_{11}$ and -35.91 ㏈ $S_{22}$ at 2.16 GHz, and +5.34 ㏈m II $P_{ 3}$ at 10 MHz channel spacing.g.g.g.

• Proceedings of the IEEK Conference
• /
• 2003.07b
• /
• pp.947-950
• /
• 2003

본 논문에서는 고속 적외선 무선 데이터통신(IrDA) 에 사용되는 트랜스임피던스 증폭기(Transimpedance Amplifier)를 설계하였다. 트랜스임피던스 증폭기는 잡음을 최소화하기 위해 PMOS 차동 구조로 설계하였으며 입력과 출력의 피드백을 통해 주위의 빛에 의해 발생되는 photocurrent 에 의한 DC 옵셋을 제거하였다 또한 공통 게이트(CG)와 Regulated Cascode Circuit (RGC)을 추가하여 대역폭(Bandwidth)을 향상시켰다. 설계한 회로는 0.25 um CMOS 공정을 이용하였으며 트랜스임피던스 이득은 200 MHz의 대역폭에서 10 KΩ (80 dBΩ )이다. 전체 전력 소비는 18 mW이다.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.1
• /
• pp.30-36
• /
• 2001

0.35 ${\mu}{\textrm}{m}$-gate AlGaAs/InGaAs PHEMTs have been fabricated using electron beam lithography. DC and AC characteristics of PHEMTs having different gate widths and number of fingers were measured at various bias conditions. An MIMIC power amplifier operating at 35 GHz has been designed and fabricated using passive element library. The power amplifier showed gain and input reflection coefficient of 7.9 ㏈ and -15 ㏈, respectively, at 27.6 GHz.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.7 no.4
• /
• pp.76-85
• /
• 2008

In this paper, a 800 MHz 1 W cartesian feedback linearized power amplifier is designed and fabricated for TETRA handset application. For amplification of TETRA signal with 200 kHz narrow bandwidth, amplifier linearization performance of more than 30 dBc is improved through the cartesian feedback linearizer at the offset Sequency of ${\pm}25$ kHz. It is clear that the linearization performance is affected by imbalance of gain and phase between I/Q signals and also DC offset. The linearization performance can be maximized by the compensation of those influences. Cartesian feedback is suitable for a liearization technique of narrow band signal with QAM and another modulation signals, as well.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.11 s.114
• /
• pp.1105-1111
• /
• 2006

In this paper, using low-temperature co-fired ceramic(LTCC) based system-in-package(SiP) technology, a very compact power amplifier LTCC module was designed, fabricated, and then characterized for 60 GHz wireless transmitter applications. In order to reduce the interconnection loss between a LTCC board and power amplifier monolithic microwave integrated circuits(MMIC), bond-wire transitions were optimized and high-isolated module structure was proposed to integrate the power amplifier MMIC into LTCC board. In the case of wire-bonding transition, a matching circuit was designed on the LTCC substrate and interconnection space between wires was optimized in terms of their angle. In addition, the wire-bonding structure of coplanar waveguide type was used to reduce radiation of EM-fields due to interconnection discontinuity. For high-isolated module structure, DC bias lines were fully embedded into the LTCC substrate and shielded with vias. Using 5-layer LTCC dielectrics, the power amplifier LTCC module was fabricated and its size is $4.6{\times}4.9{\times}0.5mm^3$. The fabricated module shows the gain of 10 dB and the output power of 11 dBm at P1dB compression point from 60 to 65 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.3
• /
• pp.380-388
• /
• 2011

In this paper, we developed the X-band 63 watt pulsed SSPA(Solid State Power Amplifier) by using HMIC(Hybrid Microwave Integrated Circuits). The pulsed SSPA consists of power supply and 3-stage amplifier modules : pre-amplifier stage, driver-amplifier stage, final-amplifier stage. The developed pulsed SSPA provides more than 63 watts of output power with a short pulse width and the duty cycle of up to 1.2 % at $70^{\circ}C$. The fabricated module offers great than 37 dB of saturated gain across the operating band. Input and output VSWR is <1.5:1. This module has an average current of 400 mA typical and operates at a +28 $V_{dc}$ supply. The developed SSPA in this paper can apply to pulsed Doppler radar with high speed operation.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.627-633
• /
• 2011

DC/DC switching power converters are commonly used to generate a regulated DC output voltages with high efficiencies from different DC input sources. The voltage mode DC/DC converter utilizes MOSFET, inductor, and a PWM (pulse-width modulation) controller with oscillator, amplifier, and comparator, etc. to efficiently transfer energy from the input to the output at periodic intervals. The fundamental boost converter and a buck converter containing a switched-mode power supply are studied. In this paper, the electrical characteristics of DC/DC power converters are simulated by program of SPICE. In addition, power efficiency is analyzed based on the specification of each component.

• Proceedings of the KWS Conference
• /
• 2000.04a
• /
• pp.99-102
• /
• 2000

Conventionally, ZVS FB DC/DC converter was controlled by monolithic IC UC3879, which includes the functions of oscillator, error amplifier and phase-shift circuit. Also, microprocessor and DSP have been widely used for the remote control and for the immediate waveform control in ZVS FB DC/DC converter. However the conventional microprocessor controller is complex and difficult to control because the controller consists of analog and digital parts. In the case of the control of FB DC/DC converter, the output is required of driving a direct signal to the switch drive circuits by the digital controller. So, this paper presents the method and realization of designing the digital-to-phase shift PWM circuit controlled by DSP (TMX320C32) in a 2,500A, 40㎾ WS FB DC/DC converter.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.537-538
• /
• 2008

A step-down DC-DC converter with On-chip Compensation for battery-operated portable electronic devices which are designed in 0.18um CMOS standard process. In an effort to improve low load efficiency, this paper proposes the PFM (Pulse Frequency modulation) voltage mode 1MHz switching frequency step-down DC-DC converter with on-chip compensation. Capacitor multiplier method can minimize error amplifier compensation block size by 20%. It allows the compensation block of DC-DC converter be easily integrated on a chip and occupy less layout area. But capacitor multiplier operation reduces DC-DC converter efficiency. As a result, this converter shows maximum efficiency over 87% for the output voltage of 1.8V (input voltage : 3.3V), maximum load current 500mA, and 0.14% output ripple voltage. The total core chip area is $mm^2$.

• Journal of the Semiconductor & Display Technology
• /
• v.13 no.4
• /
• pp.59-63
• /
• 2014

Previous studies have selected wireless power transmission system using 2.45 GHz of ISM band, but the researches for 5.8 GHz microwave wireless power transmission have been relatively rare. The 5.8 GHz has some advantages compared with 2.45 GHz. Those are smaller antenna and smaller integrated system for RFIC. In this paper, the 5.8 GHz wireless power transmission system was developed and transmission efficiency was measured according to the distance. A transmitter sent the amplified microwaves through an antenna amplified by a power amplifier of 1W for 5.8 GHz, and a receiver was converted to DC from RF through a RF-DC Converter. In the 1W 5.8GHz wireless power transmission system, the converted currents and voltages were measured to evaluate transmission efficiency at each distance where LED lights up to 1m. The RF-DC Converter is designed and fabricated by impedance matching using full-wave rectifier circuit. The transmission-efficiency of the system shows from 1.05% at 0cm to 0.095% at 100cm by distance.