Patent
Sub networks for filter ladder networks
John M. Rollet,David R. Wise +1 more
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TLDR
In this article, it has been found that the combination of a 1/s2 element in series with a simulated 1/S element is stable and suitable for use in ladder filter networks.Abstract:
The invention concerns a subnetwork of a filter circuit which is useful for detecting the dialing tone used in a telephone system. The arrangement employs active devices such as operational amplifiers in circuit with passive resistive and capactive elements to simulate an inductance S. Although it is known to modify a gyrator circuit to produce a 1/s2 function it has hitherto been considered that the use of such simulated functions in a ladder filter network would produce an unstable arrangement. It has been found that the combination of a 1/s2 element in series with a simulated 1/s element is stable and suitable for use in ladder filter networks.read more
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References
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