Analog to frequency convertor
First Claim
1. An analog to frequency convertor for deriving by a charge quantity compensation process, an output signal proportional in frequency to the magntidue of a current or voltage input to said analog to frequency convertor, comprising:
- integrating means for receiving said input to the analog to frequency convertor to supply an output dependent thereon, said integrating means including a capacitor;
threshold circuit means coupled to said capacitor, for responding when the voltage across said capacitor reaches at least one predetermined level;
compensating charge transmitter means having its output coupled to said capacitor for supplying a constant increment of charge to said capacitor each time said threshold circuit means responds;
control circuit means coupled to said threshold circuit means for developing a periodic digital polarity signal, the logic value of which polarity signal controls both the polarity of said input to the analog to frequency convertor and the polarity of said increment of charge supplied to said capacitor, said logic value always changing at a predetermined level of said voltage across said capacitor; and
means to derive said output signal dependent upon the frequency with which said increments of charge are supplied to said capacitor.
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Abstract
An analog to frequency convertor for developing an output signal of frequency proportional to a measuring current or voltage by the charge quantity compensation method, comprising an integrator, a threshold switch downstream thereof, a compensating charge transmitter which supplies a constant compensating charge to a capacitor of the integrator each time the threshold switch responds, and a control circuit to generate a periodic digital polarity signal which controls the polarity of the measuring current or voltage and of the compensating charge transmitter and always changes its logic value at the same level of the output voltage of the integrator.
17 Citations
12 Claims
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1. An analog to frequency convertor for deriving by a charge quantity compensation process, an output signal proportional in frequency to the magntidue of a current or voltage input to said analog to frequency convertor, comprising:
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integrating means for receiving said input to the analog to frequency convertor to supply an output dependent thereon, said integrating means including a capacitor; threshold circuit means coupled to said capacitor, for responding when the voltage across said capacitor reaches at least one predetermined level; compensating charge transmitter means having its output coupled to said capacitor for supplying a constant increment of charge to said capacitor each time said threshold circuit means responds; control circuit means coupled to said threshold circuit means for developing a periodic digital polarity signal, the logic value of which polarity signal controls both the polarity of said input to the analog to frequency convertor and the polarity of said increment of charge supplied to said capacitor, said logic value always changing at a predetermined level of said voltage across said capacitor; and means to derive said output signal dependent upon the frequency with which said increments of charge are supplied to said capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An analog to frequency convertor for deriving by a charge quantity compensation process, an output signal proportional in frequency to the magntidue of a current or voltage input to said analog to frequency convertor, comprising:
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integrating means for receiving said input to the analog to frequency convertor to supply an output dependent thereon, said integrating means including a capacitor; threshold circuit means coupled to said capacitor, for responding when the voltage across said capacitor reaches at least one predetermined level; compensating charge transmitter means having its output coupled to said capacitor for supplying a constant increment of charge to said capacitor each time said threshold circuit means responds; control circuit means coupled to said threshold circuit means for developing a periodic digital polarity signal, the logic value of which polarity signal controls both the polarity of said input to the analog to frequency convertor and the polarity of said increment of charge supplied to said capacitor; and means to derive said output signal dependent upon the frequency with which said increments of charge are supplied to said capacitor.
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Specification