数字式开关电容带通滤波器设计原理

Design principle of digital switching capacitor band-pass filter

利用电容既能线性跟随单踪信号,又能抑制周期性混叠信号的双重能力,本文提出了分时传递信号的带通滤波原理及与原理相关的带通滤波器。调控电路分时传递的切换频率,将主频信号在一周期内由n条支路在其固定的1/n时段分时有效地传递,其合成即为滤波器传递的主频信号。对于其他频率成份的谐波信号,电路合成的传递函数趋于零,带通幅频曲线近于理想的窄方波,文中主要研究了n=4的滤波情形。本文为模拟信号的滤波提供了一种新的数字式处理方法与理论。

Using the double abilities of capacitor： both linear following single signal and inhibiting periodic superimposed signal, this paper presents the principle of a band-pass filter that time-division transfers signal and the filter that is related to this principle. Adjusting the switching frequency at which the signal is time-division transferred, the basic frequency signal is transferred through n branches within one signal cycle efficiently, and each branch works for a fixed 1/n of the signal period. The composed signal of the n branches is the main frequency signal transferred by the filter. For the other frequency harmonic signals, the composed transfer function of the circuit tends to zero, and the band-pass amplitude-frequency characteristic of the circuit approximates to an ideal narrow square shape. This article mainly studies the filter with n = 4. This paper presents a new digital processing method and theory for the filtering of analog signal.