To allow the size of a screen in the vertical direction to be hardly changed by suppressing variations in a triangle wave of a vertical deflection circuit with a simple circuit configuration.

A constant current source 12 supplies a current to a diode D1 in its forward direction, a second amplifier X4 amplifies a forward voltage of the diode D1 and gives the amplified voltage to a gain control terminal of a first amplifier X2, and the first amplifier X2 amplifies a triangle wave voltage received from a triangle wave generating circuit G and provides an output on the basis of an amplitude setting voltage generated by a voltage generating circuit 27 and the forward voltage of the diode D1.

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