Color gain control circuit

DETAILED DESCRIPTION I claim: 1.
A color gain control circuit characterized in that a manual gain control, the bias of which is controllable by a manipulatable voltage, and an automatic gain control, the bias of which is automatically controllable by an ACC signal, are connected in cascade between a power source and a constant current source with the automatic gain control positioned upstream of the manual gain control with respect to the power source.
2.
A color gain control circuit as defined in claim 1, characterized in that said manual gain control comprises a first differential pair of differentially connected transistors and a second differential pair of differentially connected transistors both connected to the constant current source, wherein resistor means are inserted between the second differential pair and the constant current source, and the respective output terminals of each of said first and second differential pairs are connected to each other.
3.
A color gain control circuit as defined in claim 1 or 2, characterized in that the ACC signal for said automatic gain control is obtained from a comparator for comparing the amplitudes of respective outputs from B-Y and R-Y or G-Y demodulators.
4.
A color gain control circuit as defined in any one of claims 1 or 2, characterized in that, in a color television receiver set of a type having a color killer system for stopping the manual gain control to avoid the appearance of color noises on a picture screen when the color synchronization is out of order during the receipt of a color television broadcasting, a color killer signal is disabled during at least the color burst period to allow the manual gain control to be operable.




Description:
FIELD OF TECHNOLOGY The present invention relates to a color gain control circuit for use in a color television receiver set, etc.
, and, more particularly, to a color gain control circuit of unitary structure wherein manual and automatic gain controls are connected in cascade fashion