-
公开(公告)号：KR840001466B1
公开(公告)日：1984-09-27
申请号：KR810002286
申请日：1981-06-24
Applicant: RCA CORP
Inventor： HARFORD JACK R
Abstract: An AGC system is provided which develops controllably delayed gain control signals of opposite sense for an intermediate frequency amplifier arrangement. One gain control current is applied to the collector of an output transistor. The collector of the transistor is coupled to its base by a network which includes a filter for removing signal frequency noise from the gain control signal developed at the emitter of the transistor.
-
公开(公告)号：KR830000076B1
公开(公告)日：1983-02-05
申请号：KR790002824
申请日：1979-08-18
Applicant: RCA CORP
Inventor： HARFORD JACK R
IPC: H04N5/08
Abstract: 내용없음.
-
公开(公告)号：US3628166A
公开(公告)日：1971-12-14
申请号：US3628166D
申请日：1970-06-03
Applicant: RCA CORP
Inventor： HARFORD JACK R
CPC classification number: H03F3/195 , H03G1/0017
Abstract: A wide-band amplifier including a pair of transistors is arranged in a cascode configuration. Input signals are controllably attenuated over a given range of amplitudes by a coupling network to stabilize at a predetermined amplitude those signals applied to the common-emitter transistor of the cascode pair for amplification. Such an arrangement enables the commonbase transistor of the transistor pair to develop output signals having significantly less distortion than would be present where input signals of the order of 100 millivolts or so are applied without any attenuation to the common-emitter transistor; it also enables the common-base transistor to maintain an output signalto-noise ratio substantially greater than would be the case if attenuation were employed throughout.
-
公开(公告)号：US3560865A
公开(公告)日：1971-02-02
申请号：US3560865D
申请日：1969-03-03
Applicant: RCA CORP
Inventor： HARFORD JACK R
Abstract: AN AMPLITUDE MODULATION DETECTOR CIRCUIT EMPLOYES A RECTIFIER COUPLED TO A SOURCE OF SIGNAL MODULATED CARRIER WAVES CONTAINING A DIRECT VOLTAGE COMPONENT NOT RELATED TO THE MODULATION COMPONENTS OF THE CARRIER WAVE. THE DIRECT VOLTAGE COMPONENT IS MONITORED BY A CIRCUIT, WHICH ALSO INCLUDES A RECTIFIER, TO DERIVE A VOLTAGE FOR MAINTAINING A STABLE LOW CURRENT BIAS THROUGH THE DETECTOR AMPLI-
FIER. THE RECTIFIER IN THE MONITORING CIRCUIT IS RETURNED TO A POINT OF REFERENCE POTENTIAL BY A TRANSISTOR WHOSE IMPEDANCE IS CONTROLLED AS AN INVERSE FUNCTION OF THE DETECTED SIGNAL.-
公开(公告)号：US3579133A
公开(公告)日：1971-05-18
申请号：US3579133D
申请日：1969-01-29
Applicant: RCA CORP
Inventor： HARFORD JACK R
CPC classification number: H03G1/0082 , H03G3/02
Abstract: A signal translating stage especially suited for fabrication using integrated circuit techniques including a first transistor, the transconductance of which is adjusted to effect a desired attenuation of applied input signals in response to a controllable direct voltage applied to an included second transistor, with the control voltage being applied in a manner to introduce a minimum of distortion in the attenuated signal over a wide control range.
-
Patent Agency Ranking
公开(公告)号：US3579112A
公开(公告)日：1971-05-18
申请号：US3579112D
申请日：1969-03-03
Applicant: RCA CORP
Inventor： HARFORD JACK R
CPC classification number: H03G3/3068
Abstract: In a superheterodyne receiver, IF output of tuner, together with an IF AGC bias potential, are applied via a dynamic attenuator network to an IF amplifier input electrode. Delay transistor, biased into saturation, holds off (a) a transistor serving as the active device of the attentuator network, and (b) a transistor serving as an RF AGC drive transistor, over a first range of received signal levels below a first threshold level. AGC bias variations applied to amplifier input electrode varies IF amplifier gain without affecting IF attenuator or tuner in the first range. At a given AGC bias level (to which delay transistor base is responsive) delay transistor comes out of saturation and its collector potential (to which the bases of attenuator and RF AGC transistors are responsive) varies inversely with AGC bias. At first threshold level, delay transistor collector potential departs sufficiently from saturation potential to initiate RF AGC transistor conduction, and RF AGC action commences. A full range of RF AGC action is traversed before delay transistor collector potential arrives at level-initiating attenuator transistor conduction. Beyond this second threshold level, attenuator action occurs and a negative DC feedback loop is closed which holds IF amplifier bias relatively constant. Receiver signal control thus follows sequence including at least three phases: (1) a weaksignal phase, wherein AGC action is confined to IF amplifier gain variations; (b) a medium-signal phase, wherein IF amplifier gain variations are accompanied by RF amplifier gain variations; and (c) a strong-signal phase, wherein control is confined essentially to IF attenuator action.
-
公开(公告)号：US3538448A
公开(公告)日：1970-11-03
申请号：US3538448D
申请日：1968-01-17
Applicant: RCA CORP
Inventor： HARFORD JACK R
IPC: H03G3/30
CPC classification number: H03G3/3052
-
公开(公告)号：CA1185359A
公开(公告)日：1985-04-09
申请号：CA404103
申请日：1982-05-31
Applicant: RCA CORP
Inventor： HARFORD JACK R
Abstract: Television receiver employs a synchronous video detector system, and includes an AFT detector (21) responsive to carrier waves supplied by reference amplifier (15) of synchronous detector (17) system. A peak detector (31), indepedent of the synchronous video detector and the receiver's automatic gain control (29) system, is responsive to the output of the receiver's IF amplifier (13), and supplies an output to a voltage comparator (33). When the comparison indicates the IF output swing exceeds a threshold value, the AFT detector is disabled to avoid an AFT "lockout" condition.
-
公开(公告)号：CA1123065A
公开(公告)日：1982-05-04
申请号：CA337137
申请日：1979-10-05
Applicant: RCA CORP
Inventor： HARFORD JACK R
Abstract: RCA 73,331 A circuit is provided for protecting an amplifier from signal overload upon the application of strong signals at the input to the amplifier. A unidirectionally conducting semiconductor device and a capacitor are serially coupled between the input to the amplifier and ground. Means for maintaining a constant voltage is coupled to the junction of the semiconductor device and the capacitor. Upon the application of a strong signal at the input to the amplifier, the semiconductor device conducts current to the junction of the constant voltage means and the capacitor, causing the voltage across the capacitor to increase. The constant voltage means senses this voltage increase, and responds by opposing the voltage increase so as to maintain a substantially constant voltage across the capacitor. The constant voltage at the junction of the semiconductor device and the capacitor maintains the semiconductor device in a low impedance state, thereby attenuating the strong signal at the input to the amplifier. The circuit may also be operated in a second mode, in which current conduction by the semiconductor device and constant voltage means is under the control of the AGC system to attentuate the input signal to an I.F. amplifier.
-
公开(公告)号：PL231729A1
公开(公告)日：1982-01-18
申请号：PL23172981
申请日：1981-06-17
Applicant: RCA CORP
Inventor： HARFORD JACK R
Abstract: An AGC system is provided which develops controllably delayed gain control signals of opposite sense for an intermediate frequency amplifier arrangement. One gain control current is applied to the collector of an output transistor. The collector of the transistor is coupled to its base by a network which includes a filter for removing signal frequency noise from the gain control signal developed at the emitter of the transistor. The filter also provides a controllable means for adjusting the tuner AGC delay point. Both gain control signals are supplied at low impedance transistor electrodes so that the opposite sense signals require no further amplification before being applied to the I.F. amplifiers.
-
-
-
-
-
-
-
-
-
Search Results
43
records
(took 0.024 seconds)
