Electrical transmission or interconnection systems – Nonlinear reactor systems – Parametrons
Patent
1991-09-04
1992-06-23
Jackson, Jr., Jerome
Electrical transmission or interconnection systems
Nonlinear reactor systems
Parametrons
357 13, 357 12, 307303, H01L 2992
Patent
active
051247615
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a semiconductor apparatus which can eliminate an influence exerted by a parasitic capacitance, and which can alleviate restrictions on the driving condition.
BACKGROUND ART
In a prior-art home VTR, in a recording system and a reproducing system there is commonly provided a so-called ACC circuit in which an amplitude of a color burst signal is detected to control a gain of a chrominance signal amplifier thereby maintaining an amplitude of the chrominance signal constant FIG. 4 shows a previously-proposed semiconductor apparatus used in this ACC circuit.
The VTR and the ACC circuit according to the prior art will be described with reference to FIGS. 1 and 2.
FIG. 1 shows an example of an arrangement of a reproducing system of a prior-art VTR.
Referring to FIG. 1, reproduced outputs from a pair of rotary magnetic heads 1A and 1B are commonly supplied through a head change-over switch 2 and an amplifier 3 to a high-pass filter 4 and a low-pass filter 5 from which there are separated an FM luminance signal Y.sub.FM and a down converted chrominance signal C.sub.L.
The FM luminance signal Y.sub.FM is supplied to a luminance signal processing circuit 7 which includes an FM-demodulator 6, and a reproduced luminance signal Y therefrom is supplied to an adder 8.
The down-converted chrominance signal C.sub.L is supplied through a chrominance signal amplifier 11 to a frequency converting circuit 12, in which it is converted to an original carrier chrominance signal C in response to an output from a local oscillator not shown The reproduced carrier chrominance signal C from the frequency converting circuit 12 is supplied to the adder 8 through a bandpass filter 13 whose center frequency is a color subcarrier frequency fsc, and the adder 8 derives a color video signal
A burst gate circuit 14 is supplied with the output of the bandpass filter 13, and the reproduced color burst signal extracted thereby is supplied to an ACC detector 15. The detected output therefrom is supplied through an ACC circuit 20 to the chrominance signal amplifier 11 of which the gain is therefore ACC-controlled.
In order to protect the chrominance signal from a flicker caused by an output level difference when the characteristics of the rotary magnetic heads 1A and 1B are not equal, the ACC circuit 20 employs capacitors 21A and 21B of the same capacitance to form time constant circuits having time constants different in field. The time constant circuits are changed-over by the switching pulse from a pulse generator 9 in synchronism with the switching operation of the rotary heads 1A and 1B.
As shown in FIG. 2, in the prior-art ACC circuit 20, the capacitors 21A and 21B are respectively connected to output terminals of differential amplifiers (comparing circuits) 22A and 22B. The differential amplifiers 22A and 22B are alternately supplied at non-inverting input terminals thereof with a detected output V.sub.15 applied to an input terminal 20i of the ACC circuit 20 from the ACC detector 15 through a change-over switch 23i at every field, and they are also commonly supplied at their inverting input terminals with a reference voltage Vr of a reference voltage source 24. The differential amplifiers 22A and 22B respectively supply the corresponding capacitors 21A and 21B with output currents corresponding to differences between the ACC detected output voltage V.sub.15 and the reference voltage Vr. The terminal voltages across the capacitors 21A and 21B are alternately supplied through buffer amplifiers (buffers) 25A and 25B and a change-over switch 23o to an output terminal 20o at every field. The switches 23i and 23o are changed in position at every field in response to the switching pulse from a control terminal 20c in a ganged-fashion.
In the conventional ACC circuit shown in FIG. 2, the two signal systems respectively including the differential amplifiers 22A and 22B are switched by the switches 23i and 23o, which provides a large-sized circuit scale and a complicated arrangement. Further, even w
REFERENCES:
patent: 4151610 (1979-04-01), Suzuki et al.
patent: 4214252 (1980-07-01), Goerter
patent: 4672403 (1987-06-01), Jennings
Senuma Toshitaka
Yamaguchi Futao
Dang Hung Xuan
Jackson, Jr. Jerome
Sony Corporation
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