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本文给出了实现单位元波开关电容滤波器适配器的几个新电路。这些新适配器电路仪用一个单位增益器和一个两相时钟信号,而且电路特性对主寄生电容效应极不敏感。文中还分析了次寄生电容(包括电容器上极板对衬底的寄生电容和开关的寄生电容)对电路特性的影响。分析表明,整个次寄生电容效应表现为对反射系数的影响。通过调整一个电容,就可以把这种本来就很小的影响降至更小。另外,本文的电路还非常适合用于实现程控滤波器,可以有效地进行实时语声综合。最后,给出了一个五阶切比雪夫低通滤波器的例子。实验结果与理论相符。
This article presents several new circuits for implementing a unitary wave switched capacitor filter adapter. These new adapter circuit units use a unity gain and a two-phase clock signal, and the circuit characteristics are extremely insensitive to the primary parasitic capacitance effect. The paper also analyzes the secondary parasitic capacitance (including the capacitor plate parasitic capacitance of the substrate and the parasitic capacitance of the switch) on the circuit characteristics. The analysis shows that the entire secondary parasitic capacitance effect appears as the influence on the reflection coefficient. By adjusting a capacitor, you can minimize the effect of this has been small. In addition, the circuit in this paper is also very suitable for implementing program-controlled filters, which can effectively synthesize real-time speech. Finally, an example of a fifth-order Chebyshev low-pass filter is given. The experimental results are in line with the theory.