High voltage generation using low voltage devices
First Claim
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1. A charge pump system, comprising:
- a first charge pump section connected to receive an input voltage and a first clock signal, including;
three or more capacitors, each capacitor having a first plate and a second plate; and
switching circuitry connected to receive the first clock signal, whereby the capacitors are alternately connectable according to the first clock signal in a first phase and a second phase,wherein, in the first phase, the first plate of each of the capacitors is connected to receive the input voltage and the second plate of each of the capacitors is connected to ground, andwherein, in the second phase, the capacitors are connected in series such that the second plate of a first capacitor in the series is connected to receive the input voltage, and for each capacitor after the first capacitor in the series, the second plate is connected to the first plate of a preceding capacitor in the series, and the first plate of a last capacitor in the series is connected to supply an output voltage of the first charge pump section, wherein the switching circuitry comprises;
a first number of PMOS transistors connected in series between the first plate of the first capacitor in the series and the second plate of a second capacitor in the series, anda second number of PMOS transistors having control gates connected to the first plate of the first capacitor in the series, wherein the second number of PMOS transistors are connected in series between the first plate of the second capacitor and the second plate of a third capacitor in the series,wherein the second number is larger than the first number.
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Abstract
A charge pump design suitable for generating high voltages employs multiple low voltage capacitors and low voltage transfer switches, with a limited number of high voltage devices. This is designed such that during a first clock phase, capacitors are each connected between an input voltage and ground and, during a second clock phase all the capacitors are connected in series to generate the required voltage. Both the switches (PMOS) and as well the capacitors are realized as low voltage devices. The ability to use low voltage devices can significantly reduce the area and also a reduction in current consumption relative to the usual high voltage charge pumps which uses high voltage devices.
332 Citations
22 Claims
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1. A charge pump system, comprising:
a first charge pump section connected to receive an input voltage and a first clock signal, including; three or more capacitors, each capacitor having a first plate and a second plate; and switching circuitry connected to receive the first clock signal, whereby the capacitors are alternately connectable according to the first clock signal in a first phase and a second phase, wherein, in the first phase, the first plate of each of the capacitors is connected to receive the input voltage and the second plate of each of the capacitors is connected to ground, and wherein, in the second phase, the capacitors are connected in series such that the second plate of a first capacitor in the series is connected to receive the input voltage, and for each capacitor after the first capacitor in the series, the second plate is connected to the first plate of a preceding capacitor in the series, and the first plate of a last capacitor in the series is connected to supply an output voltage of the first charge pump section, wherein the switching circuitry comprises; a first number of PMOS transistors connected in series between the first plate of the first capacitor in the series and the second plate of a second capacitor in the series, and a second number of PMOS transistors having control gates connected to the first plate of the first capacitor in the series, wherein the second number of PMOS transistors are connected in series between the first plate of the second capacitor and the second plate of a third capacitor in the series, wherein the second number is larger than the first number. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method, comprising:
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alternately connecting N capacitors in a first phase and a second phase according to a first clock signal by use of switching circuitry, wherein each of the N capacitors comprises a first conductor and a second conductor, wherein N is an integer greater than two, and wherein connecting the N capacitors in the first phase includes; connecting the first conductors of the N capacitors to receive an input voltage while the second conductors of the N capacitors are connected to ground, and wherein connecting the N capacitors in the second phase includes; connecting the N capacitors in series from a first capacitor in the series to a last capacitor in the series, and supplying an output voltage from the first conductor of the last capacitor in the series, wherein connecting the N capacitors in series comprises; connecting the first conductor of a (M−
1)st capacitor in the series and the second plate of an Mth capacitor in the series through a first number of PMOS transistors, where M is an integer between two and N; andconnecting the first plate of the Mth capacitor and the second plate of an (M+1)st capacitor in the series through a second number of PMOS transistors having control gates connected to the first plate of the (M−
1)st capacitor,wherein the second number is larger than the first number. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification