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Detail
Registered VARIABLE GAIN AMPLIFIER AND VARIABLE GAIN AMPLIFIER MODULE
- Inventors
- Young Ho Kim, Park Mun Yang, Yu Hyun Kyu
- Application No.
- 11510403 (2006.08.25)
- Publication No.
- 20070126501 (2007.06.07)
- Registration No.
- 7391260 (2008.06.24)
- Country
- UNITED STATES
- Project Code
- 05MB3400, H/W Reconfigurable SoC for Next Generation Intelligent Integrated Terminal, Cho Kyoung Ik
- Abstract
- 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.