Successive approximation type AD converter and sensor device
First Claim
1. A successive approximation type AD converter comprising:
- a first capacitance DA converter that samples a first input analog signal and outputs a voltage corresponding to a sampled value;
a second capacitance DA converter that samples a second input analog signal and outputs a voltage corresponding to a sampled value;
a comparator that compares an output of the first capacitance DA converter and an output of the second capacitance DA converter;
a successive approximation logic unit that supplies a control signal to the first capacitance DA converter and the second capacitance DA converter on the basis of a comparison result of the comparator; and
an in-phase voltage detection and supply circuit that, in a sampling period, supplies an in-phase voltage obtained by impedance voltage division of the first input analog signal and the second input analog signal to the first capacitance DA converter and the second capacitance DA converter,wherein the first capacitance DA converter samples the first input analog signal with reference to the in-phase voltage in the sampling period, the second capacitance DA converter samples the second input analog signal with reference to the in-phase voltage,after the sampling period ends, the comparator compares the output of the first capacitance DA converter and the output of the second capacitance DA converter, output voltages of the first capacitance DA converter and the second capacitance DA converter are changed by the control signal of the successive approximation logic unit on the basis of a comparison result, comparison processing is repeated, and thereby, a digital signal of a successive approximation result is output.
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Abstract
A successive approximation type AD converter includes an in-phase voltage detection and supply circuit that supplies an in-phase voltage obtained by impedance voltage division of a first input analog signal and a second input analog signal to a first capacitance DA converter and a second capacitance DA converter. The first capacitance DA converter samples the first input analog signal with reference to the in-phase voltage, and the second capacitance DA converter samples the second input analog signal with reference to the in-phase voltage. After the sampling period ends, a comparator compares the output of the first capacitance DA converter and the output of the second capacitance DA converter, output voltages of the first capacitance DA converter and the second capacitance DA converter are changed by the control signal of a successive approximation logic unit on the basis of a comparison result, and comparison processing is repeated.
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Citations
15 Claims
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1. A successive approximation type AD converter comprising:
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a first capacitance DA converter that samples a first input analog signal and outputs a voltage corresponding to a sampled value; a second capacitance DA converter that samples a second input analog signal and outputs a voltage corresponding to a sampled value; a comparator that compares an output of the first capacitance DA converter and an output of the second capacitance DA converter; a successive approximation logic unit that supplies a control signal to the first capacitance DA converter and the second capacitance DA converter on the basis of a comparison result of the comparator; and an in-phase voltage detection and supply circuit that, in a sampling period, supplies an in-phase voltage obtained by impedance voltage division of the first input analog signal and the second input analog signal to the first capacitance DA converter and the second capacitance DA converter, wherein the first capacitance DA converter samples the first input analog signal with reference to the in-phase voltage in the sampling period, the second capacitance DA converter samples the second input analog signal with reference to the in-phase voltage, after the sampling period ends, the comparator compares the output of the first capacitance DA converter and the output of the second capacitance DA converter, output voltages of the first capacitance DA converter and the second capacitance DA converter are changed by the control signal of the successive approximation logic unit on the basis of a comparison result, comparison processing is repeated, and thereby, a digital signal of a successive approximation result is output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A successive approximation type AD converter of differential input, the successive approximation type AD converter comprising:
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a first capacitance DA converter;
a second capacitance DA converter;
a comparator;
a successive approximation logic unit; and
an in-phase voltage detection and supply circuit,wherein the in-phase voltage detection and supply circuit performs impedance voltage division with respect to a first input analog signal and a second input analog signal in a sampling period to connect the result to a first terminals of the first capacitance DA converter and the second capacitance DA converter, the first input analog signal and the second input analog signal are connected to second terminals of the first capacitance DA converter and the second capacitance DA converter and sampling is performed, after the sampling period ends, the comparator compares the output of the first capacitance DA converter and the output of the second capacitance DA converter, output values of the first capacitance DA converter and the second capacitance DA converter are changed by the control signal of the successive approximation logic unit on the basis of a comparison result, successive approximation processing is repeated, and thereby, a digital value is output.
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13. A sensor device comprising a sensor that outputs a differential detection signal, and a successive approximation type AD converter in which the differential detection signal of the sensor is input, wherein the successive approximation type AD converter comprises:
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a first capacitance DA converter that samples a first input analog signal and outputs a voltage corresponding to a sampled value; a second capacitance DA converter that samples a second input analog signal and outputs a voltage corresponding to a sampled value; a comparator that compares an output of the first capacitance DA converter and an output of the second capacitance DA converter; a successive approximation logic unit that supplies a control signal to the first capacitance DA converter and the second capacitance DA converter on the basis of a comparison result of the comparator; and an in-phase voltage detection and supply circuit that, in a sampling period, supplies an in-phase voltage obtained by impedance voltage division of the first input analog signal and the second input analog signal to the first capacitance DA converter and the second capacitance DA converter, the first capacitance DA converter samples the first input analog signal with reference to the in-phase voltage in the sampling period, the second capacitance DA converter samples the second input analog signal with reference to the in-phase voltage, after the sampling period ends, the comparator compares the output of the first capacitance DA converter and the output of the second capacitance DA converter, output voltages of the first capacitance DA converter and the second capacitance DA converter are changed by the control signal of the successive approximation logic unit on the basis of a comparison result, comparison processing is repeated, and thereby, a digital signal of a successive approximation result is output. - View Dependent Claims (14, 15)
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Specification