CMOS IF/Baseband Analog Signal Processor for CDMA based IS-95 Communication System

• Main Authors: Bay Shin Lien, 連倍興
• Other Authors: Chorng Kuang Wang
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/27387007350586717879

碩士 === 國立臺灣大學 === 電機工程學研究所 === 90 === This thesis introduces power detected type feedback control IF/Baseband automatic gain control system (AGC) for CDMA based IS-95 communication system. This system covers wide dynamic range input signals and is robust against phase error caused by communication channel with rapid system settling time. Various amplitude architectures are discussed and compared with the issues of yield cost, stability and responding time. From these points of view, feedback control type AGC takes advantages over stability and cost issues and by using power detection mechanism, the AGC system can be robust against phase error caused by severe channel environment. With enough loop bandwidth, the close loop AGC system can accommodate rapid fading channel and settles within required timing specifications. In the aspects of circuit design, a new quadrature wave shaping buffer architecture and squaring-summing circuit as a power detector are proposed. The I/Q wave shaping buffer can generate exact 90° quadrature output signals and gains 12dB more phase noise response for the oscillator due to its architecture characteristics. The power detector is designed by employing MOS inherent I-V characteristics and thus no individual squaring and summing blocks are needed for the input complex signals. The circuits, i.e. VGA, mixer, ring oscillator, 7th-order Chebyshev low pass filter, output wideband amplifier, loop filter, and opamp based integrator are implemented to consist of the AGC system. At last, the circuits of the AGC system are verified from the post-layout simulation results. This chip is fabricated by 0.35mm 1P4M TSMC CMOS technology. The chip occupies 1380mm´1380mm yield area and consumes 24mW under 2V power supply.