• 한국전기전자재료학회논문지
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• 제21권4호
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• pp.321-328
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• 2008

In this paper, variable gain amplifier(VGA) with a gain slope controller has been proposed and verified by circuit simulations and measurements. The proposed VGA has a gain control, gain slope switch and variable gain range. The input source coupled pair with diode connected load is used for VGA gain stage. The gain slope controller with switch can control VGA gain slope. The proposed VGA is fabricated in $0.18{\mu}m$ CMOS process for multi -standard wireless receiver. The proposed two stage VGA consumes min. 2.0 mW to max. 2.6 mW in gain control range and gives input IP3 of -3.77 dBm and NF of 28.7 dB at 1.8 V power supply under -25 dBm, 1 MHz input. The proposed VGA has 37 dB(-16 dB $\sim$ 21 dB) variable gain range, and 8 dB gain range control per 0.3 V control voltage, and can provide variable gain, positive and negative gain slope control, and gain range control. This VGA characteristics provide design flexibility in multi-standard wireless receiver.

• 한국통신학회논문지
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• 제31권3A호
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• pp.356-359
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• 2006

A monolithic SiGe HBT variable gain driver amplifier(VGDA) with high dB-linear gain control and high linearity has been developed as a driver amplifier with ground-shielded microstrip lines for 5-GHz transmitters. The VGDA consists of three blocks such as the cascode gain-control stage, fixed-gain output stage, and voltage control block. The circuit elements were optimized by using the Agilent Technologies' ADSs. The VGDA was implemented in STMicroelectronics' 0.35${\mu}m$ Si-BiCMOS process. The VGDA exhibits a dynamic gain control range of 34 dB with the control voltage range from 0 to 2.3 V in 5.15-5.35 GHz band. At 5.15 GHz, maximum gain and attenuation are 10.5 dB and -23.6 dB, respectively. The amplifier also produces a 1-dB gain-compression output power of -3 dBm and output third-order intercept point of 7.5 dBm. Input/output voltage standing wave ratios of the VGDA keep low and constant despite change in the gain-control voltage.

• 대한기계학회논문집A
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• 제31권11호
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• pp.1077-1082
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• 2007

We present a micromechanical active amplifier, inspired from the principle of the outer hair cells in cochlea, amplifying both displacement and force. The present micromechanical active amplifier modulates the resonant carrier motion using the variable stiffness spring whose stiffness changes proportionally to the input motion. We design, fabricate, and characterize two types of the amplifiers A and B, each having the variable stiffness spring fur the maximum displacement gain and force gain, respectively. In the experimental study, the amplifier A shows the displacement gain of 5.62, which is 2.15 times larger than that of the amplifier 3. The amplifier B shows the force gain of 10.0, resulting in 1.26 times larger value compared to that of the amplifier A. We experimentally verify that the haircell-inspired micromechanical amplifiers are capable to amplify both displacement and force.

• 전자공학회논문지
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• 제51권12호
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• pp.90-95
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• 2014

본 논문에서는 다양한 모바일 TV 규격을 지원할 수 있는 모바일 TV 튜너용 VHF 및 UHF 대역 가변 이득 저잡음 증폭기를 제안한다. 제안한 VHF 대역 가변 이득 증폭기는 외부 매칭 소자를 제거하기 위해 저항 피드백을 이용하여 저잡음 증폭기와 저주파수 잡음 특성을 개선하기 위해 PMOS 입력을 사용하는 싱글-차동 증폭기, 이득 범위를 제어하기 위해 저항 피드백 부분과 감쇄기로 구성된다. 제안한 UHF 대역 가변 이득 증폭기는 잡음 특성과 외부 간섭 신호 제거 특성을 향상시키기 위해 협대역 저잡음 증폭기와 $g_m$ 가변 방식을 이용하여 이득을 제어할 수 있는 싱글-차동 증폭기와 감쇄기로 구성된다. 제안한 VHF 및 UHF 대역 가변 이득 저잡음 증폭기는 $0.18{\mu}m$ CMOS 공정을 사용하여 설계하였고, 전원 전압 1.8 V에서 각각 22 mA와 17 mA 의 전류를 소모하면서 약 27 dB와 27 dB의 전압 이득, 1.6-1.7 dB와 1.3-1.7 dB의 잡음 지수, 13.5 dBm와 16 dBm의 OIP3의 성능을 보인다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제11권4호
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• pp.336-343
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• 2011

This paper introduces a simple variable gain amplifier (VGA) structure that shows an inherently dB-linear gain control property. Requiring no additional components for dB-linear control, the structure is compact and power efficient. The designed two-stage VGA shows a gain control range of 60dB with the gain error in the range of ${\pm}0.4$ dB. The power consumption including the output buffer is 20.4 mW from 1.2 V supply voltage with bandwidth of 630 MHz. The prototype was fabricated in a 0.13 ${\mu}m$ CMOS process and the VGA core occupies 0.06 $mm^2$.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.873-876
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• 1999

A variable gain amplifier(VGA) for wireless LAN is designed using active feedback. The amplifier is controlled by the gate voltage in the feedback path. This amplifier has more than 30㏈ gain variation and a improved linearity in the RF receiver block as input voltage increases. An active feedback topology is used by P-HEMT and is also analyzed for FET equivalent model.

• 한국산업정보학회논문지
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• 제18권5호
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• pp.1-8
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• 2013

본 논문은 수동소자를 사용하지 않고 선형성 향상을 얻는 가변이득증폭기(VGA, variable gain amplifier) 설계에 관련된 것이다. 이 제안된 VGA는 전류 귀환 증폭기 구조를 이용하고, 이득은 입력단과 귀환부의 트랜스컨덕턴스(GM) 비로 얻어진다. 선형성과 높은 이득을 얻기 위하여 귀환 트랜스컨덕턴스에 전류 분할 기법과 소스 축퇴(degeneration) 기법을 사용하였다. 이득의 변화는 가변 정류기로 입력 트랜스컨덕턴스의 바이어스 전류를 변화시켜 얻을 수 있다. 이 VGA는 $0.35{\mu}m$ CMOS공정을 사용하여 설계하였고, 저 전력을 위해 sub-threshold 영역에서 동작시키게 하였다. 가변 이득은 23dB~43dB의 결과를 얻도록 하였고, 소모 전류는 3.3V에서 $2.82{\mu}A{\sim}3{\mu}A$ 이다. 이 VGA가 차지하는 칩 면적은 $120{\mu}m{\times}100{\mu}m$이다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.579-587
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• 2014

This paper presents a variable gain amplifier (VGA) for an analog front-end (AFE) of ultrasound medical imaging. This VGA has a closed-loop topology and shows a 37-dB-linear characteristic with a single-stage amplifier. It consists of an op-amp, a non-binary-weighted capacitor array, and a gain-control block. This non-binary-weighted capacitor array reduces the required number of capacitors and the complexity of the gain-control block. The VGA has been fabricated in a 0.35-mm CMOS process. This work gives the largest gain range of 37 dB per stage, the largest P1 dB of 9.5 dBm at the 3.3-V among the recent VGA circuits available in the literature. The voltage gain is controlled in the range of [-10, 27] dB in a linear-in-dB scale with 16 steps by a 4-bit digital code. The VGA has a bandpass characteristic with a passband of [20 kHz, 8 MHz].

• ETRI Journal
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• 제31권2호
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• pp.234-236
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• 2009

We present a novel operational amplifier preset technique for a switched-capacitor circuit to reduce the acquisition time by improving the slewing. The acquisition time of a variable gain amplifier (VGA) using the proposed technique is reduced by 30% compared with a conventional one; therefore, the power consumption of the VGA is decreased. For additional power reduction, a programmable capacitor array scheme is used in the VGA. In the 0.13 ${\mu}m$ CMOS process, the VGA, which consists of three-stages, occupies 0.33 $mm^2$ and dissipates 19.2 mW at 60 MHz with a supply voltage of 1.2 V. The gain range is 36.03 dB, which is controlled by a 10-bit control word with a gain error of ${\pm}0.68$ LSB.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.218-220
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• 2004

A new wide-band VCO topology using Miller capacitance is proposed. Contrary to conventional VCO using the Miller capacitance where the variable amplifier gain is negative, the proposed VCO uses both the negative and positive variable amplifier gain to enhance the frequency tuning range significantly. The proposed VCO is simulated using HSPICE. The simulations show that 410MHz and 220MHz frequency tuning range are obtained using the negative .and positive variable amplifier gain, respectively. The tuning range of the proposed VCO is $23\%$ of the center frequency(2.8GHz). The phase noise is -104dBc/Hz at 1MHz offset by simple model. The operating current is only 3.84mA at 2.5V power supply.