Kinescope driver with output load resistor coupled to kinescope cathode via two paths including a further resistor and a series coupled buffer amplifier and capacitor

摘要

A current source (70) is coupled to supply an output current to a circuit node (60) proportional to a video input signal (R). A first resistor (65), coupled between the circuit node (60) and a source of supply voltage (68), develops an amplified video signal which is coupled from the circuit node to the cathode (K1) of a kinescope (20) via a second resistor (85). A capacitor (100 or 110) is provided having a first electrode coupled to the cathode (K1) of the kinescope (20) and having a second electrode coupled to the circuit node (60) via an amplifier(90). Advantageously, the combined resistance of the two resistors imparts gamma correction to the kinescope, the capacitor and amplifier compensate for stray capacitance associated with the cathode without subjecting low frequency components to any possibility of distortion in the amplifier. Additionally, the capacitance (110) may be varied as a function of the beam current for stabilizing the overall driver amplifier frequency response.