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US 7,403,151 B2Granted
Switch control circuit, ΔΣ modulation circuit, and ΔΣ modulation AD converter
AssigneeSanyo Electric Co., Ltd.
InventorAkinobu Onishi
Life of this patent
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Abstract
A switch control circuit turns on/off second and third switches, while turning off/on first and fourth switches, in a complementary manner in an integrator constituted by using a switched capacitor including the first to fourth switches and, where the first and fourth switches are turned off and the second and third switches are turned on, the switch control circuit turns on the second switch before turning off the fourth switch.
Claims14
A switch control circuit of an integrator, the integrator including:
- an operational amplifier that has an input terminal and an output terminal;
- a first capacitor that has first and second electrodes, the first electrode being electrically connected to the output terminal of the operational amplifier, the second electrode being electrically connected to the input terminal of the operational amplifier;
- a second capacitor that has third and fourth electrodes;
- a first switch that intervenes between the third electrode of the second capacitor and the input terminal of the operational amplifier;
- a second switch that causes a reference voltage to be applied to the third electrode of the second capacitor;
- a third switch that causes an input voltage to be applied to the fourth electrode of the second capacitor;
- and
- a fourth switch that causes the reference voltage to be applied to the fourth electrode of the second capacitor,
- the switch control circuit turning on/off the second and third switches of the integrator, while turning off/on the first and fourth switches of the integrator, in a complementary manner,
- wherein the switch control circuit turns off the first switch after turning on the first and fourth switches, turns on the second switch after turning off the first switch, and turns the fourth and third switches off and on, respectively, after turning on the second switch.
7 more elements
A ΔΣ modulation circuit comprising:
- an integrator that includes
- an operational amplifier that has an input terminal and an output terminal,
- a first capacitor that has first and second electrodes, the first electrode being electrically connected to the output terminal of the operational amplifier, the second electrode being electrically connected to the input terminal of the operational amplifier,
- a second capacitor that has third and fourth electrodes,
- a first switch that controls electric connection between the third electrode of the second capacitor and the input terminal of the operational amplifier,
- a second switch that controls application of a reference voltage to the third electrode of the second capacitor,
- a third switch that controls application of an input voltage to the fourth electrode of the second capacitor, and
- a fourth switch that controls application of the reference voltage to the fourth electrode of the second capacitor, the integrator integrating and outputting the input voltage;
- a switch control circuit that turns on/off the second and third switches, while turning off/on the first and fourth switches, in a complementary manner;
- a quantizer that quantizes and outputs the output of the integrator;
- and
- a subtraction circuit that reduces electric charge accumulated in the first capacitor depending on the output of the quantizer,
- wherein the switch control circuit turns off the first switch after turning on the first and fourth switches, turns on the second switch after turning off the first switch, and turns the fourth and third switches off and on, respectively, after turning on the second switch.
10 more elements
A method of integrating an input signal, comprising:
- providing an integrator including:
- an operational amplifier that has an input terminal and an output terminal;
- a first capacitor that has first and second electrodes, the first electrode being electrically connected to the output terminal of the operational amplifier, the second electrode being electrically connected to the input terminal of the operational amplifier;
- a second capacitor that has third and fourth electrodes;
- a first switch that intervenes between the third electrode of the second capacitor and the input terminal of the operational amplifier;
- a second switch that causes a reference voltage to be applied to the third electrode of the second capacitor;
- a third switch that causes the input voltage to be applied to the fourth electrode of the second capacitor;
- and
- a fourth switch that causes the reference voltage to be applied to the fourth electrode of the second capacitor,
- turning on/off the second and third switches of the integrator, while turning off/on the first and fourth switches of the integrator, in a complementary manner,
- wherein the switch control circuit turns off the first switch after turning on the first and fourth switches, turns on the second switch after turning off the first switch, and turns the fourth and third switches off and on, respectively, after turning on the second switch.
8 more elements
Dependencies are inferred from the claim text.