ANALOG-TO-DIGITAL CONVERTER
First Claim
1. An analog-to-digital converter circuit comprising:
- a first analog terminal receiving an input of a first analog signal;
a first input switch inputting the first analog signal to said first analog terminal;
a second analog terminal receiving an input of a second analog signal;
a second input switch inputting the second analog signal to said second analog terminal;
a first reference voltage connecting terminal supplied with a first reference voltage;
a second reference voltage connecting terminal supplied with a second reference voltage;
a first unit including a digital-to-analog converter which generates a comparison signal serving as an object of comparison of the first analog signal, the first unit taking in and retaining the first analog signal from said first analog terminal and outputting a result of comparing the comparison signal and the first analog signal;
a second unit including a digital-to-analog converter which generates a comparison signal serving as an object of comparison of the second analog signal, the second unit taking in and retaining the second analog signal from said second analog terminal and outputting a result of comparing the comparison signal and the second analog signal;
a first switch connecting in a mutually openable/closable manner an output side of said first unit to an output side of said second unit;
a comparator comparing, when said first switch is opened, a differential value between the first analog signal and the second analog signal with a differential value between the comparison signal of said first digital-to-analog converter and the comparison signal of said second digital-to-analog converter; and
an electric potential control circuit controlling a fluctuation in the electric potentials of said first analog terminal and said second analog terminal, wherein said first digital-to-analog converter has a plurality of capacitance elements, a first set of a plurality of switches connecting respective input-side terminals of said plurality of capacitance elements to any one of said first analog terminal, said first reference voltage terminal and said second reference voltage terminal, and a first common terminal connecting in common a plurality of output-side terminals facing said respective input-side terminals of said plurality of capacitance elements, wherein said second digital-to-analog converter has a plurality of capacitance elements, a second set of a plurality of switches connecting respective input-side terminals of said plurality of capacitance elements to any one of said second analog terminal, said first reference voltage terminal and said second reference voltage terminal, and a second common terminal connecting in common a plurality of output-side terminals facing said respective input-side terminals of said plurality of capacitance elements, wherein at a point of time when said first unit and said second unit take in the first analog signal and the second analog signal by said first input switch and said second input switch inputting the first analog signal and the second analog signal to said first analog terminal and said second analog terminal, said first common terminal and said second common terminal are connected to each other by said first switch, the connection between said first common terminal and said second common terminal is released when completing the take-in, and said electric potential control circuit, when said first input switch and said second input switch are opened after the completion of taking in the first analog signal and the second analog signal, restrains a fluctuation in the electric potential of said first analog terminal and the electric potential of said second analog terminal.
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Accused Products
Abstract
Included are a first DAC taking in and retaining sample data of a first analog signal and generating a comparison signal serving as an object of comparison with the first analog signal, a second DAC taking in and retaining sample data of a second analog signal and generating a comparison signal as an object of comparison with the second analog signal, a first switch connecting the first digital-to-analog converter to an output side of a second digital converter in a openable/closable manner, a comparator comparing, when the first switch is opened, a differential value between the first analog signal and the second analog signal with a differential value between an output signal of the first DAC and an output signal of the second DAC, and an electric potential control circuit controlling fluctuations in electric potentials of a first analog terminal and a second analog terminal.
31 Citations
6 Claims
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1. An analog-to-digital converter circuit comprising:
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a first analog terminal receiving an input of a first analog signal;
a first input switch inputting the first analog signal to said first analog terminal;
a second analog terminal receiving an input of a second analog signal;
a second input switch inputting the second analog signal to said second analog terminal;
a first reference voltage connecting terminal supplied with a first reference voltage;
a second reference voltage connecting terminal supplied with a second reference voltage;
a first unit including a digital-to-analog converter which generates a comparison signal serving as an object of comparison of the first analog signal, the first unit taking in and retaining the first analog signal from said first analog terminal and outputting a result of comparing the comparison signal and the first analog signal;
a second unit including a digital-to-analog converter which generates a comparison signal serving as an object of comparison of the second analog signal, the second unit taking in and retaining the second analog signal from said second analog terminal and outputting a result of comparing the comparison signal and the second analog signal;
a first switch connecting in a mutually openable/closable manner an output side of said first unit to an output side of said second unit;
a comparator comparing, when said first switch is opened, a differential value between the first analog signal and the second analog signal with a differential value between the comparison signal of said first digital-to-analog converter and the comparison signal of said second digital-to-analog converter; and
an electric potential control circuit controlling a fluctuation in the electric potentials of said first analog terminal and said second analog terminal, wherein said first digital-to-analog converter has a plurality of capacitance elements, a first set of a plurality of switches connecting respective input-side terminals of said plurality of capacitance elements to any one of said first analog terminal, said first reference voltage terminal and said second reference voltage terminal, and a first common terminal connecting in common a plurality of output-side terminals facing said respective input-side terminals of said plurality of capacitance elements, wherein said second digital-to-analog converter has a plurality of capacitance elements, a second set of a plurality of switches connecting respective input-side terminals of said plurality of capacitance elements to any one of said second analog terminal, said first reference voltage terminal and said second reference voltage terminal, and a second common terminal connecting in common a plurality of output-side terminals facing said respective input-side terminals of said plurality of capacitance elements, wherein at a point of time when said first unit and said second unit take in the first analog signal and the second analog signal by said first input switch and said second input switch inputting the first analog signal and the second analog signal to said first analog terminal and said second analog terminal, said first common terminal and said second common terminal are connected to each other by said first switch, the connection between said first common terminal and said second common terminal is released when completing the take-in, and said electric potential control circuit, when said first input switch and said second input switch are opened after the completion of taking in the first analog signal and the second analog signal, restrains a fluctuation in the electric potential of said first analog terminal and the electric potential of said second analog terminal. - View Dependent Claims (2, 3, 4)
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5. An analog-to-digital converter circuit comprising:
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a first analog terminal receiving an input of a first analog signal;
a first input switch inputting the first analog signal to said first analog terminal;
a second analog terminal receiving an input of a second analog signal, a second input switch inputting the second analog signal to said second analog terminal;
a first reference voltage connecting terminal supplied with a first reference voltage;
a second reference voltage connecting terminal supplied with a second reference voltage;
a first unit including a digital-to-analog converter which generates a comparison signal serving as an object of comparison of the first analog signal, the first unit taking in and retaining the first analog signal from said first analog terminal and outputting a result of comparing the comparison signal and the first analog signal;
a second unit including a digital-to-analog converter which generates a comparison signal serving as an object of comparison of the second analog signal, the second unit taking in and retaining the second analog signal from said second analog terminal and outputting a result of comparing the comparison signal and the second analog signal;
a first switch connecting in a mutually openable/closable manner an output side of said first unit to an output side of said second digital converter; and
a comparator comparing a differential value between the first analog signal and the second analog signal with a differential value between the comparison signal of said first digital-to-analog converter and the output signal of said second digital-to-analog converter;
wherein said first digital-to-analog converter has a plurality of capacitance elements, a first set of a plurality of switches connecting respective input-side terminals of said plurality of capacitance elements to any one of said first analog terminal, said first reference voltage terminal and said second reference voltage terminal, and a first common terminal connecting in common a plurality of output-side terminals facing said respective input-side terminals of said plurality of capacitance elements, wherein said second digital-to-analog converter has a plurality of capacitance elements, a second set of a plurality of switches connecting respective input-side terminals of said plurality of capacitance elements to any one of said second analog terminal, said first reference voltage terminal and said second reference voltage terminal, and a second common terminal connecting in common a plurality of output-side terminals facing said respective input-side terminals of said plurality of capacitance elements, wherein said plurality of capacitance elements of said first digital-to-analog converter contains a first capacitance element having a capacitance that is equivalent to ½
a capacitance of said whole plural capacitance elements of said first digital-to-analog converter, after completing the take-in of the first analog signal, any one of said first reference voltage terminal and said second reference voltage terminals is connected to an input-side terminal of said capacitance element other than said first capacitance element on the basis of a result of the comparison by said comparator, and said first reference voltage terminal is connected to the input-side terminal of said first capacitance element irrespective of the result of the comparison by said comparator, andwherein said plurality of capacitance elements of said second digital-to-analog converter contains a second capacitance element having a capacitance that is equivalent to ½
a capacitance of said whole plural capacitance elements of said second digital-to-analog converter, after completing the take-in of the second analog signal, any one of said first reference voltage terminal and said second reference voltage terminals is connected to an input-side terminal of said capacitance element other than said second capacitance element on the basis of the result of the comparison by said comparator, and said second reference voltage terminal is connected to the input-side terminal of said second capacitance element irrespective of the result of the comparison by said comparator. - View Dependent Claims (6)
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Specification