Circuit and method for reducing east-west geometry mismatch between the top and bottom of a raster display

1. A method, comprising:

generating a sawtooth signal, wherein the sawtooth signal has an amplitude;

generating a correction signal with no discontinuities, wherein the correction signal has a vertical retrace time t VR and a vertical active time t VA ;

modulating the amplitude of the sawtooth signal using the correction signal to generate a deflection signal; and

amplifying the deflection signal to generate a deflection current signal, wherein the deflection current signal is not distorted when the correction signal transitions from the vertical retrace time t VR to the vertical active time t VA .

2. The method of claim 1 , wherein the sawtooth signal is a horizontal sawtooth signal, and wherein the correction signal is a horizontal correction signal.

3. The method of claim 1 , wherein the generating the correction signal comprises generating a higher-order signal.

4. The method of claim 1 , wherein a circuit generates the correction signal, and wherein the circuit includes a level shifter.

5. The method of claim 4 , wherein the circuit includes an inverter.

6. The method of claim 4 , wherein the circuit includes a gain controller.

7. A method, comprising:

generating a sawtooth signal, wherein the sawtooth signal has an amplitude;

generating a correction signal with no discontinuities, wherein the correction signal has a vertical retrace time t VR and a vertical active time t VA ;

modulating the amplitude of the sawtooth signal using the correction signal to generate a deflection signal; and

amplifying the deflection signal to generate a deflection current signal, wherein the deflection current signal is not distorted when the correction signal transitions from the vertical retrace time t VR to the vertical active time t VA , wherein the generating the correction signal is performed by combining a first correction signal component with a second correction signal component.

8. The method of claim 7 , wherein the first correction signal component has a constant amplitude during the vertical active time t VA .

9. The method of claim 7 , wherein the second correction signal component has a constant amplitude during the vertical retrace time t VR .

10. The method of claim 7 , wherein the first correction signal component has an amplitude, and wherein the amplitude of the first correction signal component varies parabolically.

11. A horizontal deflection generator, comprising:

a circuit that generates a horizontal sawtooth signal having an amplitude; and

means for modulating the amplitude of the horizontal sawtooth signal using a horizontal correction signal to generate a horizontal deflection current signal, wherein the horizontal correction signal has no discontinuities, wherein the horizontal correction signal has a vertical active time t VA and a vertical retrace time t VR , and wherein the horizontal deflection current signal is not distorted after a transition from the vertical retrace time t VR to the vertical active time t VA .

12. The horizontal deflection generator of claim 11 , wherein the horizontal correction signal is a continuous signal.

13. The horizontal deflection generator of claim 11 , wherein the means comprises an amplifier, wherein the means generates a modulated horizontal sawtooth signal, and wherein the amplifier generates the horizontal deflection current signal by amplifying the modulated horizontal sawtooth signal.

14. The horizontal deflection generator of claim 13 , wherein the amplifier has a limited frequency bandwidth.

15. The horizontal deflection generator of claim 11 , wherein the horizontal deflection generator is part of a raster display system.

16. The horizontal deflection generator of claim 11 , wherein the horizontal deflection generator is implemented on a single integrated circuit device.

17. The horizontal deflection generator of claim 11 , wherein the horizontal deflection generator is implemented in software.

18. A horizontal deflection generator, comprising:

a circuit that generates a horizontal sawtooth signal having an amplitude; and

means for modulating the amplitude of the horizontal sawtooth signal using a horizontal correction signal to generate a horizontal deflection current signal, wherein the horizontal correction signal does not have any discontinuities.

19. The horizontal deflection generator of claim 18 , wherein the horizontal deflection generator is implemented in software.

20. The horizontal deflection generator of claim 18 , wherein the means comprises an amplifier, wherein the means generates a modulated horizontal sawtooth signal, and wherein the amplifier generates the horizontal deflection current signal by amplifying the modulated horizontal sawtooth signal.