Negative charge pump
First Claim
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1. A negative charge pump formed on a semiconductor substrate comprising:
- a power supply having a first terminal connected to said substrate and a second terminal connected to a high voltage rail;
a plurality of charging capacitors connected between said high voltage rail and said substrate, said charging capacitors connected to said high voltage rail by a first set of transistor switches and connected to said substrate by a second set of transistor switches;
an output capacitor connected between said high voltage rail and said charging capacitors, said output capacitor connected to at least one of the said charging capacitors by a third set of transistor switches;
wherein said second and third sets of switches are NMOS transistors and said first set of switches are PMOS switches.
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Abstract
A negative charge pump is disclosed. The negative charge pump may be used to drive white LEDs in one application. The negative charge pump uses predominantly n-channel transistor switches that enables a smaller integrated circuit area. Further, a soft start mechanism is used in starting the charge pump.
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Citations
3 Claims
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1. A negative charge pump formed on a semiconductor substrate comprising:
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a power supply having a first terminal connected to said substrate and a second terminal connected to a high voltage rail;
a plurality of charging capacitors connected between said high voltage rail and said substrate, said charging capacitors connected to said high voltage rail by a first set of transistor switches and connected to said substrate by a second set of transistor switches;
an output capacitor connected between said high voltage rail and said charging capacitors, said output capacitor connected to at least one of the said charging capacitors by a third set of transistor switches;
wherein said second and third sets of switches are NMOS transistors and said first set of switches are PMOS switches. - View Dependent Claims (2, 3)
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Specification