用CFA实现的Kerwin-Huelsman-Newcomb电路

The Realization of Kerwin Huelsman Newcomb Circuit by Using CFA

有源器件电流反馈放大器（ＣＦＡ）由于能够提供常值带宽和高的电压摆率，因而在模拟信号处理电路中受到了广泛的重视并得到广泛应用．对两种用电流反馈放大器实现的加法器电路，进行了数学推证，并用这两种加法器和积分器实现基于ＣＦＡ的Ｋｅｒｗｉｎ－Ｈｕｅｌｓｍａｎ－Ｎｅｗｃｏｍｂ（ＫＨＮ）电路，进行了设计和实验验证．实验结果与理论计算值吻合较好，充分证明了提出的加法器电路及所实现的基于ＣＦＡ的ＫＨＮ电路的正确性用ＣＦＡ实现的ＫＨＮ电路与Ｓｏｌｉｍａｎ用ＣＣⅡ实现的ＫＨＮ电路相比，少了两个有源器件，因而电路结构简单．而且，电路中只有同一种类型的有源器件，因而电路易于实现．同时，两种等效的加法器实现了两种形式的ＫＨＮ电路，这就为电路的优选提供了可能性．另外，该电器还具有好的级联特性．因而。

Current feedback amplifiers(CFA) have received attention in analog signal processing because they can provide not only constant bandwidths but also high slew rates. Several CFA based filters have been proposed and much work has been done by circuit transformation methods from opamp based circuits into CFA based circuits with higher performance. The purpose of this paper is to propose CFA based Kerwin Huelsan Newcomb(KHN)biquad from opamp based one. The opamp based KHN circuit is composed of two inverting integrators and a three inputs summer. For proposing CFA based KHN circuit, the CFA based integrator in was used. The key work in the paper is to propose CFA based multi inputs summer suitable for KHN circuit. Two equivalent CFA based summers and two kinds of KHN circuits were proposed in the paper. As proposed CFA based KHN circuits are equivalent to the opamp based KHN circuit, they can perform the same functions. To verify the correction of the proposed circuit, a second order lowpass filter is designed and experimented. Commercial CFAs(AD844)were used in the experiment. The experimental results are in agreement with the theoretical results except the gain at resonant frequency, and they show the validity of the proposed circuits and the related method. As compared with Solimans circuit, the proposed circuits need only three active components(CFAs) each, it means two active components are saved, so the circuits are simpler than that in . Moreover, because two equivalent CFA based circuits can be generated from the opamp based KHN circuit, higher flexibility is achieved to optimize the circuit. So, the proposed circuits are simple, practical and versatile.