单位元波开关电容滤波器的新实现

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。     

波开关电容滤波器的新实现

本文给出实现波开关电容滤波器的新方法。文中所提出的电路仅应用两相时钟,运算放大器数目较少,滤波特性不仅对主寄生电容很不敏感,而且次寄生电容对电路特性的影响也很小。波SCF完全保持了波数字滤波器所特有的灵敏度低、动态范围大、稳定性好、模块性强等许多优点。作为例子,文中给出了一个五阶PCM低通波SCF分析与实验的结果,证明了电路的优良特性。     

NOVEL LINEAR TRANSFORMATION SWITCHED-CAPACITOR FILTER DESIGN

This paper presents a novel method that is applied to realize the Linear Transformation(LT)Switched-Capacitor Filter(SCF).It adopts the Voltage Control Voltage Source(VCVS)equalized transfor-mation to revise the original LC ladder filter and induce it into 16 basic sections and then extend the princi-ple of the LT in order to fit active and 3 port networks and give out switched-capacitor circuits corre-sponding to the 16 basic sections,which can realize all four kinds of filters——LP,HP,BP,BS filters.De-signed examples are given here.An Nth order filter only requires N amplifiers and the circuit is insensitive toparasitic capacitances.The experimental results of a 3rd order elliptic LP and a 6th order elliptic BP are giv-en and agree with the theory.     

NOVEL REALIZATION OF UNIT ELEMENT WAVE SWITCHED CAPACITOR FILTER

In this paper,some novel SC-adaptor circuits are presented to realize the unit element waveswitched capacitor filter using two-phase clock signals.These circuits are insensitive to the bottomplate parasitic capacitances and request only one unit-gain buffer to realize an adaptor.The effectsof top plate parasitic capacitances and switch parasitic capacitances on an adaptor are analyzed.The results show that the effects of those are small and can be reduced further by adjusting onlyone of the capacitances.These circuits are adaptable for realizing programmable filters and veryuseful to the LPC real-time speech synthesis.As an example,a 5th order unit element low-passfilter is given.The experimental results are in excellent agreement with the theory.     

线性变换开关电容滤波器的新设计

本文给出了一种利用线性变换设计开关电容滤波器的新方法。它采用压控电压源等效变换,先修改原LC梯形滤波器,将其归纳为十六种基本节,然后将线性变换扩展到适用于含源和三端口情况,给出这十六种基本节对应的开关电容电路。用这十六种基本节可构成全部四种类型滤波器低通、高通、带通、带阻滤波器。文中给出了它们的设计例子。一个N阶滤波器只需要N个运放,且无寄生电容影响。给出的三阶椭圆低通和六阶椭圆带通的实验结果与理论分析相符。