Electrical transmission or interconnection systems – Nonlinear reactor systems – Parametrons
Patent
1984-08-13
1987-04-21
Miller, Stanley D.
Electrical transmission or interconnection systems
Nonlinear reactor systems
Parametrons
328138, 328139, 307543, 307556, 307564, H03F 100, H03B 166
Patent
active
046599959
ABSTRACT:
An active filter element of the fourth degree, to be connected in series with other such elements in forming a band-pass or band-stop filter of adjustable bandwidth, is a four-terminal network with three cascaded operational amplifiers interconnected by two mutually identical series resistors each inserted between the output of one amplifier and the noninverting input of the next one. The first operational amplifier, serving as an inverting adder, has its inverting input connected by two resistors to its own output and to the output of the third amplifier; the second and third operational amplifiers have their inverting inputs directly connected to their respective outputs to act as voltage followers. The two series resistors are longitudinal branches of respective frequency-dependent voltage dividers each further comprising a transverse branch connected to the junction of the corresponding resistor with the noninverting input of the next-following operational amplifier. The transverse branch may be, for a band-pass or a band-stop filter, a combination of a capacitor and an inductance in parallel or in series. In a particular instance, that branch is constituted by an active negative oscillatory circuit preceded by a negative-immitance converter. A fourth operational amplifier may have its inverting input connected via further series resistors to the outputs of the first and third amplifiers and its noninverting input connected via yet another resistor to the output of the second amplifier for the purpose of introducing an attenuation pole at a finite frequency. Finally, an equalizer including a fifth operational amplifier may be interposed between the first amplifier and the first series resistor.
REFERENCES:
patent: 3716729 (1973-02-01), Rollett
patent: 3886469 (1975-05-01), Rollett et al.
patent: 3987381 (1976-10-01), Szechenyi
patent: 4032857 (1977-06-01), Lum
patent: 4110692 (1978-08-01), Pradal
"Introduction to Filter Theory", by David Johnson, 1976, Prentice Hall, Inc., pp. 245-249.
"Einfacher Spannungs-Frequencz-Umsetzer", published in German Magazine Electronik, vol. 14 of 16 Jul. 1982, pp. 48-50.
"Aktives Selektivfilter mit Programmiervarer Bandbreite" by Horst Lutgens, in German Magazine Elektronik, vol. 14/16.7, 1982.
"Operational Amplifiers" edited by J. G. Graeme et al, McGraw-Hill Book Company, copyright by Burr-Brown Research Corp., Fig. 815, p. 308.
"Halbleiter-Schaltungstechnik" by U. Tietze-Ch. Schenk, 1978.
Dubno Herbert
Karl-Heinz Feistel
Miller Stanley D.
Roseen Richard
Ross Karl F.
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