이중 차동입력쌍 트랜스컨덕터를 구비한 가변이득증폭기 설계
김영호, 박문양, 유현규
- 7391260 (2008.06.24)
- An analog variable gain amplifier (VGA) adjusting a signal level of a mobile communication system is provided. More particularly, design of a VGA using an operational transconductance amplifier (OTA) having a wide linear input/output range is disclosed. The VGA includes two double-differential-pair OTAs and feedback resistors. A first differential input of a first double differential pair OTA receives an input signal from the forward stage, and a second differential input is negatively fed back through a differential output and a passive resistor. An input in which a first block of the connection structure and first and second differential inputs of a second double differential pair OTA are connected receives an output signal of the first block stage. The output is negatively fed back in series through a variable resistor whose resistance varies exponentially with an adjustment voltage from outside. According to the VGA, it is possible to provide a characteristic of linear variation of gain on a logarithmic scale with respect to a control voltage with a simple and inexpensive constitution. In addition, the VGA can be designed for a low pass filter having a conventional OTA used for a core circuit, and has a simple circuit structure. Therefore, the VGA is convenient for high integration and low-power design, and thus is appropriate for a terminal chip and so forth.
- KSP 제안 키워드
- Communication system, Core circuit, Differential input, Input signal, Logarithmic scale, Low Pass Filter, Low-Power, Low-Power design, Operational transconductance amplifier, Passive resistor, Signal level, Variable Gain, Variable Gain Amplifier(VGA), Variable Resistor, connection structure, control voltage, differential output, differential pair, low pass, mobile communication, mobile communication system, transconductance amplifier