DIFFERENTIAL CHARGE PUMP
First Claim
1. A differential charge pump comprising:
- a capacitive structure having a first plate and a second plate;
a first control branch for charging the first plate when a first signal is asserted, and discharging the first plate when a second signal is asserted;
a second control branch for discharging the second plate when the first signal is asserted, and charging the second plate when the second signal is asserted;
a first common mode branch for charging or discharging the first plate to a common mode voltage when the first signal and the second signal are at the same level; and
a second common mode branch for charging or discharging the second plate to the common mode voltage when the first signal and the second signal are at the same level.
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Accused Products
Abstract
A differential charge pump includes common mode circuitry for supplying a common mode voltage to a charging capacitor in the charge pump. The gate voltage of a reference transistor in a biasing branch of the differential charge pump is adjusted until the drain voltage of the reference transistor is equal to the common mode voltage when a specified bias current is flowing through the biasing branch. The same gate voltage and bias current are provided to a first transistor in a first common mode branch and a second transistor in a second common mode branch. The drains of the first transistor and the second transistor are connected to a first plate and a second plate, respectively, of the charging capacitor. In this manner, a desired common mode voltage is supplied to the charging capacitor.
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Citations
28 Claims
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1. A differential charge pump comprising:
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a capacitive structure having a first plate and a second plate;
a first control branch for charging the first plate when a first signal is asserted, and discharging the first plate when a second signal is asserted;
a second control branch for discharging the second plate when the first signal is asserted, and charging the second plate when the second signal is asserted;
a first common mode branch for charging or discharging the first plate to a common mode voltage when the first signal and the second signal are at the same level; and
a second common mode branch for charging or discharging the second plate to the common mode voltage when the first signal and the second signal are at the same level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for operating a differential charge pump, the method comprising:
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providing a charging capacitor having a first plate and a second plate, the first plate being separated from the second plate by a dielectric;
charging the first plate and discharging the second plate when a first signal is asserted and a second signal is deasserted;
charging the second plate and discharging the first plate when the first signal is deasserted and the second signal is asserted; and
driving the first plate and the second plate to a common mode voltage when the first signal and the second signal are at the same level. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A differential charge pump comprising:
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a first control branch coupled between a first supply voltage and a second supply voltage;
a second control branch coupled between the first supply voltage and the second supply voltage;
a capacitive structure coupled between the first control branch and the second control branch;
a first transistor coupled between the first supply voltage and a first plate of the capacitive structure;
a second transistor coupled between the first supply voltage and a second plate of the capacitive structure;
a third transistor, wherein a gate of the third transistor is connected to a gate of the first transistor and a gate of the second transistor; and
a voltage control circuit for regulating a first gate voltage at the gate of the third transistor to cause the third transistor to output a common mode voltage. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification