本論文描述一個應用在歐規陸地/手持式數位視頻廣播系統(DVB-T/H)中的類比前端電路(AFE)，主要以基頻接收端通訊系統應用為目標，其內部使用一個經由數位控制的自動增益濾波器來促進接收機的系統整合性與電路積體化程度。為了改良系統，在接收端的訊號路徑上有一個可程式化增益連續時間濾波器，它使用寬頻且低功率的全差動運算放大器，來構成一個頻寬為4MHz的六階Chebyshev低通濾波器，其動態增益範圍有53dB，並且由一階的數位控制迴路來自動調整其增益量使其輸出可達200 。在輸入振幅為200 的情況時，經由雙端輸入所模擬出的總諧波失真(THD)小於 -60dB。而此電路在操作電壓為1.8V時，其功率損耗為14.3毫瓦，已經由佈局後(post-layout)的模擬所驗證，並使用台灣積體電路公司(TSMC)所提供的0.18μm 1P6M CMOS製程來製造。 This paper describes a digitally controlled automatic gain control (AGC) for the analog front-end (AFE), in which it can be used to support the digital video broadcasting in DZIF (double conversion with zero second IF) architecture. In order for system improvement, the receiving path contains a programmable-gain filter (PGF) with the self-tuning gain circuit. This proposed continuous-time filter is a 4MHz sixth-order Chebyshev low-pass Active-RC filter is also described in detail. In addition, an wideband and low power fully-differential operation amplifier (OPA) used for building the filter. The dynamic range of the PGF, which is controlled by a digital loop to form a first order system, is 53dB. The third-harmonic distortion is less than –60dB for differential input signal up to 200 . This chip has already been fabricated in a TSMC 0.18μm standard CMOS technology while the supply voltage is 1.8V and its power consumption is 14.3 .
