Double tuned frequency selective circuit
Номер патента: GB1086807A
Опубликовано: 11-10-1967
Автор(ы): Arnt P Arntsen, Dirk J Boomgaard
Принадлежит: Westinghouse Electric Corp
Опубликовано: 11-10-1967
Автор(ы): Arnt P Arntsen, Dirk J Boomgaard
Принадлежит: Westinghouse Electric Corp
Реферат: 1,086,807. R.F. couplings; transistor receiver circuits. WESTINGHOUSE ELECTRIC CORPORATION. April 1, 1965 [April 14, 1964], No. 13863/65. Headings H3T and H4A. An R.F. continuously tunable frequency selective circuit for providing a substantially constant pass bandwidth throughout the operative range comprises two tank circuits each with inductive and variable capacitive elements, a coupling capacitor being connected between the inductive elements at one end thereof, and a common inductor being connected in series with both inductive elements at the other ends thereof. As described, a receiving antenna 10, for example for V.H.F. signals, is connected to the primary Lp of a transformer TF1 and the secondary L s of the said transformer is connected through an inductor L 3 to the top of a tuned circuit 31, which is thereby loaded with a resistive component R 1 of the antenna 10 which increases as the square of the tuned frequency. The tuned circuit 31 comprises an inductor L 1 and a variable capacitor C 1 and it is associated in a doubly tuned circuit 30 with a similar tuned circuit 32 comprising an inductor L 2 and a variable capacitor C 2 , the two capacitors C 1 , C 2 being ganged. Coupling between the tuned circuits 31, 32 is mainly by means of a common inductor L 5 connected to the lower ends of the inductors L 1 , L 2 but a capacitor C 5 is connected to the upper ends of the circuits to provide compensation at higher frequencies, so that the effective coupling varies inversely with the tuned frequency. The inductor L 2 is inductively coupled to an inductor L 4 connected to the base of a transistor TR operating in the common emitter mode in an R.F. amplifier 50. In addition, a capacitor C 6 is connected between the top ends of the inductors L 2 , L 4 so that a resistive component of the input impedance of the transistor which increases as the square of the tuned frequency is reflected across the tuned circuit 32. The transistor TR has a biasing network comprising resistors R 4 , R 5 and by-pass capacitor C 4 , and its emitter is connected to earth by a stabilizing resistor R 3 with by-pass capacitor C 3 . Output from a load resistor R L is taken to a wideband amplifier 60 which feeds a mixer stage 70.
Double-tuned circuit
Номер патента: US3582808A. Автор: Donovan C Davis. Владелец: Hoffman Electronics Corp. Дата публикации: 1971-06-01.