Design of Current-Mode Log-Domain Filters

• Main Authors: Wei-Ping Wang, 王威評
• Other Authors: Bin-Da Liu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/19788106386713886406

碩士 === 國立成功大學 === 電機工程學系 === 89 === In this thesis, we implement current-mode log-domain filters by applying MOSFET square law. With respect to different type of filters, we propose an approach to maintain the same operating range of the external current sources. We utilize MATLAB to perform the linear regression analysis of the simulation results. By applying the linear regressive equations, we can calculate the necessary currents and then substitute these currents into the filter to complete our design. We simulate first-order lowpass, second-order lowpass, second-order bandpass, and biquad filters. By connecting these low-order filters, we can compose a high-order filter. The simulation results show that the proposed circuits have the advantages of higher frequency operation (the maximum pole frequency of the first-order lowpass filter can achieve 5.2MHz), tuneablilty and modular design. In this thesis, we implement the proposed current-mode log-domain filters by UMC 2P2M 0.5µm process. The chip integrates six current-mode square root circuit modules, three grounded capacitor modules, and two cascode NMOS current mirror modules. The proposed filters can be implemented by connecting these modules. This chip can be utilized to implement a third-order lowpass filter.