Analysis and Design of Automatic Gain Control Circuits for Wireless Communication Applications

• Main Authors: Wang I-Hsin, 王逸新
• Other Authors: 張孟洲
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/36931879861139720192

碩士 === 長庚大學 === 電機工程研究所 === 90 === The target of this thesis is to analysis and designs an automatic gain control circuit for wireless communication applications. Automatic gain control circuits (AGC) are negative feedback circuits and usually employed in the systems where the amplitude of an incoming signal varies over a wide dynamic range. By this feedback loop, this circuit can automatically sense the strength of the output signal and modify the gain of variable gain amplifier to keep stable output signal strength. The application domain of such systems is growing very rapidly from sensor interfaces to charge-coupled devices (CCD)/CMOS imagers, wire or wireless communications, disk drive read channels, medical, and multimedia systems, to name a few. Especially in the wireless communications, the signal strength level will be different due to the multi-path fading and different positions. The AGC is therefore used to adjust the received signal to a rated strength level. First, we present the fundamental of AGC circuit and the conventional circuit design and what about their advantages and disadvantages. How to improve these disadvantages in circuits design. We use UMC 0.5μm 2P2M CMOS process in our design. The circuit layout use the 28 pins I/O pad which CIC provided. The chip area is 1800 μm × 1800μm. Under 5V power supply, our circuit provides 48dB dynamic range, maximal 65dB voltage gains in IF circuits, power consumption are 16.5mW. Under 3.3V power supply, the modified circuit provides 52dB dynamic range, maximal 73dB voltage gains in IF circuits, power consumption are 2.8 mW. The accepted paper (2002 IEEE International Conference on Electronics, Circuits and Systems) is given in Appendix.