電流模式高斯濾波器之設計

Abstract

高斯濾波器不論是在影像處理或是通訊系統中均扮演著極重要的角色。本 論文提出一個以全差動式，閘極接地回授積分器(fully differ- ential integrator with grounded gate feedback)所構成的高頻率七階雙線性 切換式電流高斯濾波器(high frequency seventh order bi- linear switched current Gaussian filter)。為了達到較低的敏感度，我們採 用階梯濾波器型式(Ladder Type)。另外我們也提出一套切換式電流濾波 器的設計和模擬方法。切換式電流濾波器使用 0.8um SPDM CMOS 製程， 晶片面積2.07 mm^2。量測結果顯示取樣頻率可達5MHz，3dB頻寬是200kHz 。在5V供應電壓下,量測到的動態範圍(dynamic range)是60dB(THD=0.3%, fs=3MHz, 40KHz輸入訊號)，損耗功率小於4mW/pole。 Gaussian filter plays an important role in image processing, computer vision and communication system. In this paper an acc- urate high-frequency seventh order bilinear switched-current Gaussian filter based on fully differential integrators with grounded-gate feedback is presented. To achieve good sensitivi- ty, we start the design with a passive LC-ladder filter and si- mulate LC-ladder filter in active form. We also proposed a de- sign methodology and simulation method of switched-current fil- ter. The prototype filter was implemented on a standard 0.8um single-poly double-metal CMOS process and occupied a total die area of 2.07 mm^2. Experimental results show an accurate res- ponse for sampling frequencies up to 5MHz.The filter achieved a passband edge(-3dB frequency) of 200kHz. Using 5V power su- pply, the measured dynamic range is 60dB (THD=0.3\%, fs=3MHz, 40kHz input signal) and the power dissipation is less than 4mW/ pole.