Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Unwanted signal suppression
Patent
1996-01-17
1998-03-10
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Unwanted signal suppression
327552, 327103, 330305, 330109, 330258, 330254, H03F 345, H03K 522
Patent
active
057266000
ABSTRACT:
An active filter circuit component includes an all NPN bipolar tunable Gm cell and a positive current source (PCS) for supplying common mode current. The tunable Gm cell includes a fixed Gm cell having transconductance G.sub.f, a current divider and recombination circuit that together effectively multiply G.sub.f by a tuning factor .alpha., where -1.ltoreq..alpha..ltoreq.1, without effecting the cell's common mode current I.sub.cm. The PCS includes a pair of unity gain inverting single ended amplifiers that are connected in antiparallel across a pair of matched resistors. Alternately, the resistors can be connected across the inverting and non-inverting sides of a differential amplifier. A constant voltage is applied across the resistors to supply I.sub.cm, while maintaining a common mode resistance of R/2 and a differential mode resistance approaching infinity.
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Cosand Albert E.
Jensen Joseph F.
Raghavan Gopal
Callahan Timothy P.
Denson-Low W. K.
Duraiswamy V. D.
Hughes Aircraft Company
Le Dinh T.
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