Abstract: A parabolic signal generator (100) for use in a cathode ray tube (CRT) display circuit, comprising: programmable delay means (110) for receiving a CRT horizontal flyback signal and for producing a trigger signal which is delayed relative to the horizontal flyback signal by a programmable predetermined time; ramp generating means (130, 140) coupled to receive the trigger signal from the programmable delay means for producing a symmetric ramp signal in response to the trigger signal; and parabola generating means (150) coupled to receive the ramp signal from the ramp generating means for producing the parabolic signal. Since the trigger signal delay is programmable, it can be adjusted to match the delay of a range of external components. Since the ramp signal is symmetric it does not require the use of complex blanking circuitry to suppress spuriae.

Abstract: A control circuit (100) which receives horizontal synchronising pulses (265) and generates a horizontal drive output signal (455) for a cathode ray tube (CRT) display. The horizontal control circuit (100) generates two ramp signals. A first ramp signal (410) for horizontal position adjustment of an image on the CRT display, and a second ramp signal (440) for propagation delay compensation of a deflection circuit (155) coupled to the CRT display. The control circuit (100) also provides digital of control of the duty cycle of the horizontal drive signal (455).

Abstract: A circuit (10) for generating a voltage ramp signal (V.sub.RAMP) having minimum amplitude variation over a large frequency range has been provided. The circuit includes a comparator (40) for comparing a voltage across a ramp capacitor (32) with a reference voltage. From the result of this comparison, a sampling capacitor (16) is discharged during the time that the voltage ramp signal is less than the reference voltage and charged during the time that the voltage ramp signal is greater than the reference voltage. The resulting voltage across the sampling capacitor is held and fed back to a transconductance amplifier (20) which adjusts the current that charges the ramp capacitor thereby adjusting the peak amplitude of the voltage ramp signal.