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Analog/digital converter and method for controlling the same

  • US 6,812,875 B2
  • Filed: 09/26/2002
  • Issued: 11/02/2004
  • Est. Priority Date: 09/27/2001
  • Status: Expired due to Fees
First Claim
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1. A method of converting an analog input signal to a digital output signal by an analog/digital converter including a digital/analog converter outputting a first signal, a low-pass filter provided with a difference signal between the input signal and the first signal and outputting a filtered difference signal, an analog comparator provided with the filtered difference signal and outputting a second signal which is a positive or negative polarity unit value, and a digital/analog converter controller outputting a third signal, the analog/digital converter controlling the third signal to make the first signal approximate to the analog input signal in order to generate the digital output signal corresponding to the analog input signal from a row of the third signal, the method comprising:

  • causing the digital/analog converter controller to take one of a first to third accumulation mode; and

    causing the digital/analog converter controller to output the third signal which is generated by accumulating a variable value one after another at a variable interval, wherein in the first accumulation mode, the third signal is generated by accumulating a first value at a first interval, and the digital/analog converter controller switches to the second accumulation mode when count of continued second signals with a same polarity reaches a threshold, in the second accumulation mode, the third signal is generated by accumulating a value whose absolute value is greater than a last accumulated value at a same interval as a last interval or accumulating a same value as a last accumulated value at an interval shorter than a last interval, and the digital/analog converter controller switches to the third accumulation mode when the polarity of the second signal changes, and in the third accumulation mode, the third signal is generated by accumulating a value whose absolute value is smaller than a last accumulated value at a same interval as a last interval or accumulating a same value as a last accumulated value at an interval longer than a last interval, and the digital/analog converter controller switches to the first accumulation mode when a current interval reaches the first interval.

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