Abstract: A cathode ray tube focusing circuit includes a first operational amplifier for receiving a sawtooth wave signal from the vertical deflection circuit of a cathode ray tube video circuit and for producing a parabolic output signal from the sawtooth wave signal. Also included is a second operational amplifier for receiving both the parabolic signal produced by the first operational amplifier and a parabolic wave signal produced by the S-correction capacitor of the horizontal deflection circuit of the cathode ray tube video circuit. The second operational amplifier inverts the parabolic wave signal received from the first operational amplifier and adds this inverted signal to the parabolic wave signal received from the horizontal deflection circuit to produce a parabolic signal envelope. This parabolic signal envelope is inverted, amplified and supplied to the focus electrode of the cathode ray tube to modulate the focus electrode's static voltage.