不等波纹函数低通原型的理论及应用

本文提出不等波纹函数低通原型，并对其理论进行初步探讨。切比雪夫函数及最平坦型巴特活兹函数皆为其特例。文中给出不等波纹函数的几个性质，最后给出两个应用实例，消除耦合环自感部分的影响；抑制高次模的微带圆盘腔带通滤波器。     

微波晶体管、场效应管管芯的不等波纹函数型阻抗匹配网络

本文给出对RC串联型,并联型负载的不等波纹函数型阻抗匹配网络的综合方法.以HFET-1000管芯为例,用不等波纹函数型综合与补偿方法得到的6-12GHz的输入输出阻抗匹配网络与传统的切比雪夫型相比,所用的L,C元件数不足后者的一半且其增益、稳定性及平坦度均有明显的改善.     

馒头形曲线图像中频放大器

目前用分立元件组成的图像中频放大器都毫无例外地采用参差调谐(对双耦回路而言是参差阻尼)的办法来实现众所周知的幅度响应特性。为了设计方便,通常先设计一个低通原型网络,然后再转换至带通。这里可供选择的低通原型响应函数有三种:巴特沃斯响应函数(平顶型响应);贝塞尔响应函数(尖顶型响应);巴特沃斯——汤姆逊结合型响应函数(馒头型响应)。汤姆逊是贝塞尔响应函数的提出者,因此这种结合型响应函数实际上就是巴特沃斯——贝塞尔结合型响应函数,本文将对这三种响应函数的优、缺点作一比较和提供一个结合型响应的计算实例。并首先讨论一下实际的阶跃响应。     

可精确综合的超宽阻带等波纹微带低通滤波器

利用公比线网络的可综合特性,设计实现了一种具有宽阻带特性和带内等波纹响应的传输线低通滤波器。该滤波器的原始设计以一段具有Z型拓扑的平行耦合线节为核心,在其四个独立端口处对称加载两对开路枝节线。当所有的传输线元件的电长度均相同时,对上述网络加以分析并得到完整的传输函数。利用平移匹配法,可以在满足指定截止频率和波纹系数的约束下,令其传输函数满足一组可调的等波纹响应。最后,利用开路扇形贴片等效低阻抗加载枝节线,完成实物滤波器的制作。测试与仿真结果吻合良好,验证了设计方法的有效性和正确性。     

微波滤波器相—频特性的不等波纹函数分析方法

本文简单地介绍不等波纹函数和它的综合方法，并对微波滤波器相－频特性的分析方法作了详细的介绍。实际应用表明，理论计算与测量结果相符甚好。     

基于椭圆球面波函数的数字带通滤波器设计

为设计频谱性能优良的有限冲激响应( FIR)数字带通滤波器,从窗函数的性质及选择指标出发,分析了椭圆球面波函数( PSWF)作为窗函数的优势;在此基础上根据数字滤波器设计的原理和要求,选择0阶基带椭圆球面波函数作为窗函数设计数字带通滤波器,并利用微分方程状态转移矩阵逼近的PSWF求解算法,给出了基于PSWF的FIR数字带通滤波器设计方法。理论分析和仿真结果表明：PSWF数字带通滤波器具有较低的设计复杂度,与Kaiser滤波器和Blackman滤波器相比,其旁瓣衰减有超过7 dB的优势,且具有与两种滤波器相当的通带波纹波动和过渡带宽。     

低功耗、低灵敏度有源带通滤波器设计的新方法

提出运用低通到带通的频率变换法与阻容细化法相结合的思想,直接利用2阶的低通(LP)滤波器原型电路实现4阶低功耗、低灵敏度的带通(BP)滤波电路的设计新方法。具体而言,通过对低通原型滤波电路进行阻抗变换以及时其对应的RC电路实现所谓“有损的LP-BP变换”,就可以实现带通(BP)滤波电路的设计。选用2阶切比雪夫(Chebyshev)低通滤波器电路为原型,给出4阶带通滤波器的具体设计过程,并通过PSpice软件来验证此种方法的可行性和实用性。     

耦合二次节型开关电流带通滤波器的改进双线性设计

本文采用改进双线性变换，以一种新型双二次节为基块进行开关电流（ＳＩ）带通滤波器的设计。这种双二次节是用本文提出的双抽样方式ＳＩ改进型通用积分器构成的。文中介绍了耦合二次节型全极点及有限传输零点带通滤波器的设计方法。用该方法设计的ＳＩ滤波电路具有较好的高频特性，并能保持无源原型的低灵敏度特点。文中给出了Ｃｈｅｂｙｓｈｅｖ和Ｅｌｌｉｐｔｉｃ带通滤波器设计的实例。     

基于Matlab的模拟滤波器设计与仿真

巴特沃思、切比雪夫模拟低通滤波器通常是设计模拟高通、带通和带阻滤波器的原型,先按给定频率响应巴特沃思、切比雪夫低通Ha（s）逼近,然后由选定Ha（s）实现二端口网络的电路结构和参数值。在此对达林顿T型和П型电路结构的滤波器元件参数进行了编程计算,并对其系统函数的幅频特性进行仿真。仿真结果符合设计要求,该方法便捷,程序具有可扩展性。     

采用钽硅集成电路的频率加强网络(FEN)滤波器

介绍一种经济的有源RC集成滤波器的设计方法。把复杂的滤波器网络分解成二阶滤波器节的链接,这种二阶节滤波器由钽薄膜RC网络和集成运算放大器组成。对于任意要求的十进频率和任意希望的滤波器函数(亦即,低通、高通、带通、带阻、全通等等),两块积木单元是有效的。一块积木单元实现低Q,并包括一个放大器;另一块积木单元实现高Q,包含有两个放大器。这种相当多用的方法根据:1)把给定的二阶函数分解成低Q渐近近似函数和有源频率加强网络的链接,2)利用钽和硅集成电路特性而得到。     

Canonical lowpass prototype network for symmetric coupled-resonator bandpass filters

A lowpass prototype network that represents a canonical realisation for symmetric coupled-resonator bandpass filters is presented. A synthesis procedure for the prototype is outlined.     

Exact design of stray-insensitive switched-capacitor lowpass ladder filters from unit-element prototypes

A new technique is described in which stray-insensitive SC lowpass ladder filters of the LDI type are designed without the need for network synthesis. These filters exactly simulate the response of a unit element cascade prototype filter and may be designed with a usable frequency range up to one half the sampling frequency. This design procedure requires no more than simple hand calculation.     

Frequency transform synthesis method for cross-coupled resonator bandpass filters

In this letter, an improved synthesis method for equal-ripple cross-coupled resonator bandpass filter is proposed based on the frequency transform method and Atia's method. In this method, the conventional lowpass prototype method is revised by replacing the low pass prototype with the frequency transform method. The detailed element extraction procedure in z-domain is given. Also the coupling matrix reduction implemented by optimization algorithm is described. This method is powerful for filter synthesis with asymmetric frequency response and complex transmission zeros. The design examples are presented and the experimental results validate its effectiveness.     

A Low-Pass Prototype Network for Microwave Linear Phase Filters

A new approximation theory is presented for a low-pass prototype filter which simultaneously optimizes both the passband amplitude and phase response of the scattering transfer coefficient over the same finite band. This closed form solution is expressed in terms of single polynomial, which is readily generated through a simple recurrence formula, and has been termed the equidistant linear phase polynomial since its phase deviation from linearity vanishes at equidistant points along the real frequency axis. A synthesis procedure is presented for the realization of this transfer function using a resistively terminated, symmetrical, lossless, two-port network where extensive use is made of the immittance inverter concept. The even-mode admittance, which defines the network, possesses a simple closed form representation in terms of the equidistant linear phase polynomial and its derivative, and consequently, the entire theory is derived in an analytic form. Typical performance characteristics are graphically presented for networks of up to 14th degree, illustrating the superiority of this new approach over any other known form of approximation theory for selective linear phase filters.     

Synthesis of lowpass lc ladder networks

A simple verification of the continued-fraction expansion method for the synthesis of simple lowpass LC ladder networks is given. A subroutine to calculate filter components by this method has been written; the subroutine can also be used for testing whether a polynomial is of Hurwitz type or not.     

Exact design of highpass switched-capacitor filters of the LDI type

The letter presents a technique by means of which stray-insensitive SC highpass ladder filters may be designed without the need for network synthesis. The starting point is a unit-element cascade (i.e. lowpass prototype from which the corresponding highpass filter is obtained by direct frequency transformation.     

一种微波多工器的网络综合方法研究

在滤波器多项式综合基础上,将多项式综合技术在多工器上做了推广,将传统的多项式综合技术从传统的双端口网络拓展到多端口网络,并且给出综合实例。该方法是在归一化频率中综合考虑各路滤波器之间的相互影响,运用迭代算法综合得到多工器的的特征多项式。最终综合结果满足设计指标,同时也验证了这种方法的可行性。