摘要:

Modified versions of the canonic forms of the scattering matrix and the transfer scattering matrix of complex lossless 2-ports are presented. In this way, these canonic forms become more natural extensions of those in the real case.

DOI:10.1049/ip-g-1.1981.0028

出版商:IEE    

年代:1981

数据来源: IET

摘要:

The two most frequently used techniques for solving the low-Qapproximation problem of filters are reviewed. It is found that the global multiple-pole approximation (GMPA) supplies transfer functions with more attractive features with respect to the partial approximation (PA) technique, in the case of frequency responses with assigned shape.

DOI:10.1049/ip-g-1.1981.0029

出版商:IEE    

年代:1981

数据来源: IET

摘要:

This paper shows how a rational transfer function can be constructed from phase polynomials such that, at given frequency points, the transfer function has prespecified phases and perfect power transmission. The frequency points do not have to be equally spaced, and the phase response does not have to be linear. The resulting transfer function is generally realisable, although there are some exceptional cases. Formulas for the reflection and transmission coefficients are given in closed form, which are easily implemented on a desktop computer.

DOI:10.1049/ip-g-1.1981.0030

出版商:IEE    

年代:1981

数据来源: IET

摘要:

Generalised quadrature-modulation (QM) circuits, introduced by Saraga, can be used to process independently the two sidebands of a double-sideband signal. Such circuits can be realised as a cascade of ‘lattice-type’ sections in which the arms of the lattice are linear, time-invariant, 2-port networks. This paper investigates the sensitivity of the transmission zeros (which exist at the frequencies of perfect quadrature) of the overall QM circuit to variations in the transfer functions of the lattice-arm networks. It is shown that variations occurring in the final section of a cascaded QM circuit can destroy the perfect quadrature, and hence the ‘potential’ transmission zeros, produced by earlier perfect sections. An example is given to illustrate the effect.

DOI:10.1049/ip-g-1.1981.0031

出版商:IEE    

年代:1981

数据来源: IET

摘要:

For specific bandpass requirements, three differentRC-active filters, using generalised impedance convertors, are synthesised, and their passive and active sensitivities are compared.

DOI:10.1049/ip-g-1.1981.0032

出版商:IEE    

年代:1981

数据来源: IET

摘要:

In 1967, Saraga provided useful clarification of the factors involved in minimising the effect, on the performance of a 2nd-order Sallen-Key filter (in particular itsQ-factor), of variations in its active and passive components. There existed at that time noautomaticmeans of minimising the variation in circuit performance ensuing from component tolerances. For each class of circuit, a theoretical study - such as that of Saraga's for the Sallen-Key filter - was needed to provide guidelines for the designer.It is now possible to carry out such a minimisation by means of an iterative algorithm. The aim of this paper is to bring such an algorithm to the notice of filter designers, to demonstrate its application to the 2nd-order Sallen-Key filter, and to show how other factors (e.g. less than 100% yield) which are not tractable analytically can easily be taken into account.

DOI:10.1049/ip-g-1.1981.0033

出版商:IEE    

年代:1981

数据来源: IET

摘要:

RC-active filters can be realised by cascaded single amplifier sections of second order ins=jw. General expressions for the changes in the overall transfer functionT(s)caused by deviations of the amplifier gainsviare derived. A pole-zero assignement minimising the sensitivity ofT(s)with respect tovjand simultaneously maximising the dynamic range is presented and demonstrated by means of an example.

DOI:10.1049/ip-g-1.1981.0034

出版商:IEE    

年代:1981

数据来源: IET

摘要:

A method for inverting any polynomial matrix, including cases in which the lowest and highest matrix coefficients are both singular, is described. An application to network sensitivity analysis is presented.

DOI:10.1049/ip-g-1.1981.0035

出版商:IEE    

年代:1981

数据来源: IET

摘要:

We show how to derive state-variable biquadratic sections with lowest possible sensitivity to their integrators. The resulting structures turn out to satisfy the condition for optimum dynamic range given by Mullis and Roberts [1]. The sensitivity optimum obtained is very ‘strong’ in the sense that these biquads simultaneously attain lower bounds for several practical measures of sensitivity. Furthermore, it is shown that this class of filters exhibits sensitivities that are either equal to or lower than those of doubly-terminatedLCladders.

DOI:10.1049/ip-g-1.1981.0036

出版商:IEE    

年代:1981

数据来源: IET

摘要:

The scaling of signal levels in multiple-feedback filters is presented in a systematic way, as an operation on a cutset of the corresponding signal-flow graph. This operation leads to an interesting summed sensitivity invariant.

DOI:10.1049/ip-g-1.1981.0037

出版商:IEE    

年代:1981

数据来源: IET