Method and apparatus for dc restoration using feedback
AssigneeRGB Systems, Inc.
InventorsRaymond William Hall, Donald E. Parreco
Life of this patent
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Abstract
A feedback circuit for restoration of DC in video signals is presented. A sample pulse representing the back porch of an incoming video signal is generated from the horizontal sync signal. The sample pulse triggers a sample and hold circuit to acquire the correct offset voltage in the output signal during this back porch period. The offset voltage feeds back through a summing node upstream of either the circuit causing the offset or an input amplifier thereby restoring the video signal to the desired DC voltage level with respect to ground.
Claims6
A feedback circuit for compensating for DC offset in an output signal comprising:
- a sampling circuit configured to sample said output signal at a time during which a DC amplitude of an input signal has a known value to obtain a DC offset value;
- a compensation circuit for applying an inverse of said DC offset value to said input signal.
A method for compensating for DC offset in an output signal comprising:
- sampling the output signal at a time during with the DC amplitude of an input signal has a known value to obtain a DC offset value;
- subtracting said DC offset value from the input signal.
Dependencies are inferred from the claim text.