Offset cancellation circuit and method of reducing pulse pairing
First Claim
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1. An offset cancellation circuit, comprising:
- a differentiator circuit having an input coupled for receiving an input signal with a DC offset and having an output for providing a differentiated signal with a DC offset;
a summing junction having first and second inputs and an output, said first input receiving said differentiated signal with said DC offset, said output providing an offset corrected signal; and
a first amplifier circuit having an input coupled to said output of said summing junction and having an output coupled to said second input of said summing junction for providing an offset correction signal to remove said DC offset from said differentiated signal.
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Abstract
An offset cancellation circuit corrects DC offset appearing at the input of a comparator circuit. The first input of a summing junction receives an input signal containing DC offset. The output of the summing junction drives the input of the comparator and a feedback amplifier, the latter of which returns to the second input of the summing junction. Any DC offset is processed through the feedback amplifier where it subtracts from the input signal for providing zero DC offset at the input of the comparator.
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Citations
15 Claims
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1. An offset cancellation circuit, comprising:
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a differentiator circuit having an input coupled for receiving an input signal with a DC offset and having an output for providing a differentiated signal with a DC offset; a summing junction having first and second inputs and an output, said first input receiving said differentiated signal with said DC offset, said output providing an offset corrected signal; and a first amplifier circuit having an input coupled to said output of said summing junction and having an output coupled to said second input of said summing junction for providing an offset correction signal to remove said DC offset from said differentiated signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of canceling a DC offset in an input signal, comprising the steps of:
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differentiating the input signal for providing a differentiated signal with a DC offset; inverting an offset correction signal for providing an inverted offset correction signal; summing said inverted offset correction signal with said differentiated signal with said DC offset for removing said DC offset and providing an offset corrected signal; and amplifying said offset corrected signal for providing said offset correction signal.
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9. In an integrated circuit a timing qualification circuit, comprising:
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a differentiator circuit having an input coupled for receiving an input signal and having an output for providing a differentiated signal with a DC offset; a summing junction having first and second inputs and an output, said first input being coupled for receiving said differentiated signal having said DC offset, said output providing an offset corrected signal; a comparator circuit having an input and an output, said input being coupled to said output of said summing junction for receiving said offset corrected signal, said output changing state at each zero crossing of said offset corrected signal corresponding to a peak of said input signal; a first amplifier circuit having an input coupled to said input of said comparator and having an output coupled to said second input of said summing junction for providing an offset correction signal to remove said DC offset from said differentiated signal; and a zero-crossing detector having an input coupled to said output of said comparator circuit and having an output for providing a clock pulse at said change of state of said output of said comparator corresponding to said peak of the input signal. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification