DC offset compensation device
First Claim
1. A DC offset compensation device for compensating DC offset included in an input signal, said device comprising:
- level detecting means for detecting variation in amplitude of the input signal to generate and output a level signal which defines a head portion of the input signal;
time constant controlling means for generating and for outputting a time constant control signal based on the level signal;
compensating means for subtracting an estimate of the DC offset from a value of the input signal to output a compensation output; and
estimating means for receiving the compensation output, for estimating the DC offset of the input signal based on the compensation output with a time constant which varies according to the time constant control signal, and for outputting the estimate to feedback to said compensating means.
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Accused Products
Abstract
A level detector 2 detects variation of the amplitude of an input signal a to output a level signal b representing HIGH or LOW in order to define the head portion of the input circuit a. A time constant control signal 3 generates a time constant control signal c based on the level signal b to control a time constant of an estimator 4 so as to make the time constant small for a prescribed period from a time when the level signal b varies from HIGH to LOW. The estimator 4 estimates DC offset included in the input signal a with the a time constant variation according to the time constant control signal c to output an estimate d. A compensator 1 subtracts the estimate d from the input signal a to obtain a compensation output. Therefore, in the estimator 4, the speed of estimating the DC offset is different between a period corresponding to the head portion of the input signal a and other periods. Thus, a DC offset compensation device can be configured to be capable of fast DC offset compensation at the head portion of the input signal a and stable DC offset compensation at the other portions.
118 Citations
22 Claims
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1. A DC offset compensation device for compensating DC offset included in an input signal, said device comprising:
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level detecting means for detecting variation in amplitude of the input signal to generate and output a level signal which defines a head portion of the input signal; time constant controlling means for generating and for outputting a time constant control signal based on the level signal; compensating means for subtracting an estimate of the DC offset from a value of the input signal to output a compensation output; and estimating means for receiving the compensation output, for estimating the DC offset of the input signal based on the compensation output with a time constant which varies according to the time constant control signal, and for outputting the estimate to feedback to said compensating means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 16, 20, 21, 22)
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13. A DC offset compensation device for compensating DC offset included in an input signal, said device comprising:
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level detecting means for detecting variation in amplitude of the input signal to generate and output a level signal which defines a head portion of the input signal; time constant controlling means for generating and for outputting a time constant control signal based on the level signal; compensating means for subtracting an estimate of the DC offset from a value of the input signal to output a compensation output; and estimating means for receiving the input signal, for estimating the DC offset of the input signal with a time constant which varies according to the time constant control signal, and for outputting the estimate to feed forward to said compensating means. - View Dependent Claims (14)
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17. A DC offset compensation device for compensating DC offset included in an input signal, said device comprising:
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compensating means for subtracting an estimate of the DC offset from a value of the input signal to output a compensation output; level detecting means for detecting variation in amplitude of the compensation output to generate and output a level signal which defines a head portion of the input signal; time constant controlling means for generating and outputting a time constant control signal based on the level signal; and estimating means for receiving the compensation output, for estimating the DC offset of the input signal based on the compensation output with a time constant which varies according to the time constant control signal, and for outputting the estimate to feedback to said compensating means. - View Dependent Claims (18, 19)
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Specification