• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.770-773
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• 2002

Two sinusoidal voltage-controlled oscillators using linear operational transconductance amplifiers are presented in this paper: One is based on the positive-feedback bandpass oscillator model and the other on the negative-feedback Colpitts model. The bandpass VCO consists of a noninverting amplifier and a current-controlled LC-tuned circuit which is realized by two linear OTA's and two grounded capacitors, while the Colpitts VCO consists of an inverting amplifier and a current-controlled LC-tuned circuit realized by three linear OTA's and three grounded capacitors. Prototype circuits have been built with discrete components. The experimental results have shown that the Colpitts VCO has a linearity error of less than 5 percent, a temperature coefficient of less than rm 100 ppm/$^{circ}C$, and a $pm1.5 Hz $frequency drift over an oscillation frequency range from 712Hz to 6.3kHz. A total harmonic distortion of 0.3 percent has been measured for a 3.3kHz oscillation and the corresponding peak-to-peak amplitude was 1V. The experimental results for bandpass VCO are also presented.

• 한국통신학회논문지
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• 제19권1호
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• pp.83-90
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• 1994

본 논문에서는 옵셋 전압을 이용하여 선형범위를 증가시킨 MOS트랜스컨덕터로 자이레이터를 구성하고, VLSI에 적합하도록 수동회로망을 구성하는 부유인덕터, 부유저항, 접지저항을 자이레이터로 모의하였다.EH한 설계 예로써 자이레이터를 이용하여 바터워스 필터를 설계하였으며, 트랜스컨덕터의 출력저항의 바이상성에 기인된 주파수천이의 특성을 보이며 필터를 구현하였다.

• 대한전자공학회논문지SD
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• 제44권8호
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• pp.1-7
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• 2007

고주파 응용을 위한 AB급 바이폴라 선형 트랜스컨덕터들을 제안한다. 이들 트랜스컨덕터는 전압 폴로워, 저항기, 그리고 전류 폴로워로 구성된다. 폴로워 회로들은 트랜스리니어 셀들로 실현되기도 하고, 단위-이득 버퍼들로 실현되기도 한다. 제안된 트랜스컨덕터들은 8 GHz 바이폴라 트랜지스터-어레이 파라미터를 이용하여 SPICE 시뮬레이션 되었다. 시뮬레이션 결과는, 트랜스리니어 셀들을 이용한 트랜스컨덕터가 단위-이득 버퍼들을 이용한 그것보다 더 좋은 선형성을 가지는데 반해, 후자는 전자보다 더 좋은 온도 특성과 더 높은 입력 저항을 가진다는 것을 보여준다. 제안된 트랜스컨덕터들의 실용성을 검증하기 위하여, 이들 트랜스컨덕터로 중간 주파수(IF) 대역의 4차 대역-통과 여파기를 구현하였다.

• 스마트미디어저널
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• 제4권2호
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• pp.55-61
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• 2015

A bandwidth-enhanced ultra-wide band (UWB) CMOS balun-LNA is implemented as a part of a software defined radio (SDR) receiver which supports multi-band and multi-standard. The proposed balun-LNA is composed of a single-to-differential converter, a differential-to-single voltage summer with inductive shunt peaking, a negative feedback network, and a differential output buffer with composite common-drain (CD) and common-source (CS) amplifiers. By feeding the single-ended output of the voltage summer to the input of the LNA through a feedback network, a wideband balun-LNA exploiting negative feedback is implemented. By adopting a source follower-based inductive shunt peaking, the proposed balun-LNA achieves a wider gain bandwidth. Two LNA design examples are presented to demonstrate the usefulness of the proposed approach. The LNA I adopts the CS amplifier with a common gate common source (CGCS) balun load as the S-to-D converter for high gain and low noise figure (NF) and the LNA II uses the differential amplifier with the ac-grounded second input terminal as the S-to-D converter for high second-order input-referred intercept point (IIP2). The 3 dB gain bandwidth of the proposed balun-LNA (LNA I) is above 5 GHz and the NF is below 4 dB from 100 MHz to 5 GHz. An average power gain of 18 dB and an IIP3 of -8 ~ -2 dBm are obtained. In simulation, IIP2 of the LNA II is at least 5 dB higher than that of the LNA I with same power consumption.