Power supply circuit
First Claim
1. A power supply circuit comprising:
- a first power supply rail;
a second power supply rail;
a first MOSFET having a gate, a source, a drain, and a body region between the source and drain, the body region being connected so as to be at the same potential as the source, and the source and drain being connected in series with the second power supply rail, the arrangement being such that application of a suitable potential to the gate is able to switch the MOSFET to an on state in which a conductive channel is opened in the body region between the source and drain to carry a power supply current through the first MOSFET; and
signal generation circuitry arranged to generate a signal indicative of a conductive state of the first MOSFET,the signal generation circuitry comprising reference voltage generation means connected to said source and arranged to generate a reference voltage, said reference voltage being a predetermined potential difference from the source potential, and a second MOSFET having a second gate, a second source, a second drain, and a second body region between the second source and second drain, the second body region being connected so as to be at the same potential as the drain of the first MOSFET, and the second gate being connected to receive said reference voltage, the arrangement being such that when the potential of the drain of the first MOSFET falls a predetermined voltage below the reference voltage the second MOSFET is switched to an on state in which a second conductive channel is opened in the second body region between the second source and the second drain, the signal being dependent upon the state of the second MOSFET.
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Accused Products
Abstract
A power supply circuit has a first MOSFET having a body region between the source and drain. The body region is connected so as to be at the same potential as the source. Application of a suitable potential to the gate causes the MOSFET to switch to a conductive on state. The power supply circuit also has signal generation circuitry, which generates a signal indicative of a conductive state of the first MOSFET. The signal generation circuitry generates a reference voltage of a predetermined potential difference from the source potential. The power supply circuit further comprises a second MOSFET having a body region connected so as to be at the same potential as the drain of the first MOSFET, and the second gate is connected to receive the reference voltage. When the potential of the drain of the first MOSFET falls a predetermined voltage below the reference voltage the second MOSFET is switched to a conductive on state between the second source and the second drain, the signal being dependent upon the state of the second MOSFET.
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Citations
24 Claims
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1. A power supply circuit comprising:
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a first power supply rail; a second power supply rail; a first MOSFET having a gate, a source, a drain, and a body region between the source and drain, the body region being connected so as to be at the same potential as the source, and the source and drain being connected in series with the second power supply rail, the arrangement being such that application of a suitable potential to the gate is able to switch the MOSFET to an on state in which a conductive channel is opened in the body region between the source and drain to carry a power supply current through the first MOSFET; and signal generation circuitry arranged to generate a signal indicative of a conductive state of the first MOSFET, the signal generation circuitry comprising reference voltage generation means connected to said source and arranged to generate a reference voltage, said reference voltage being a predetermined potential difference from the source potential, and a second MOSFET having a second gate, a second source, a second drain, and a second body region between the second source and second drain, the second body region being connected so as to be at the same potential as the drain of the first MOSFET, and the second gate being connected to receive said reference voltage, the arrangement being such that when the potential of the drain of the first MOSFET falls a predetermined voltage below the reference voltage the second MOSFET is switched to an on state in which a second conductive channel is opened in the second body region between the second source and the second drain, the signal being dependent upon the state of the second MOSFET. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An integrated circuit comprising:
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a common substrate having an upper surface and a lower surface and comprising a semiconductor substrate of a first conductivity type, a lower surface of the semiconductor substrate being the lower surface of the common substrate, and an epitaxial layer of semiconductor material of the first conductivity type formed on the semiconductor substrate; a first well of semiconductor material of a second conductivity type extending from the upper surface of the common substrate into the epitaxial layer; a second well of semiconductor material of said second conductivity type extending from the upper surface of the common substrate into the epitaxial layer, said second well being separate from said first well; a first MOSFET having a gate, a source, a drain, and a body region between the source and drain, the body region being connected so as to be at the same potential as the source; a second MOSFET having a second gate, a second source, a second drain, and a second body region between the second source and second drain, the second body region being connected so as to be at substantially the same potential as the drain of the first MOSFET, wherein the first MOSFET is a vertical power MOSFET, the source of the first MOSFET comprising a conductive contact to the upper surface of the common substrate arranged to contact the first well and at least one source region of semiconductor material of said first conductivity type extending from the upper surface into the first well, the drain of the first MOSFET comprising a conductive contact to the lower surface of the semiconductor substrate, and the body region of the first MOSFET comprising at least a portion of the first well; and wherein the second MOSFET is a lateral MOSFET, the source of the second MOSFET comprising a conductive contact to the upper surface of the common substrate arranged to contact a second source region of semiconductor material of said first conductivity type extending from the upper surface into the second well, the drain of the second MOSFET comprising a conductive contact to the upper surface of the common substrate arranged to contact a drain region of semiconductor material of said first conductivity type extending from the upper surface into the second well, and wherein the second body region of the second MOSFET comprises at least part of said second well. - View Dependent Claims (22, 23)
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24. An integrated circuit comprising:
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a common substrate having an upper surface and a lower surface and comprising a semiconductor substrate of a first conductivity type, a lower surface of the semiconductor substrate being the lower surface of the common substrate, and an epitaxial layer of semiconductor material of the first conductivity type formed on the semiconductor substrate; a first well of semiconductor material of a second conductivity type extending from the upper surface of the common substrate into the epitaxial layer; a second well of semiconductor material of said second conductivity type extending from the upper surface of the common substrate into the epitaxial layer, said second well being separate from said first well; a first MOSFET having a gate, a source, a drain, and a body region between the source and drain, the body region being connected so as to be at the same potential as the source; a second MOSFET having a second gate, a second source, a second drain, and a second body region between the second source and second drain, wherein the first MOSFET is a vertical power MOSFET, the source of the first MOSFET comprising a conductive contact to the upper surface of the common substrate arranged to contact the first well and at least one source region of semiconductor material of said first conductivity type extending from the upper surface into the first well, the drain of the first MOSFET comprising a conductive contact to the lower surface of the semiconductor substrate, and the body region of the first MOSFET comprising at least a portion of the first well; and wherein the second MOSFET is a lateral MOSFET, the source of the second MOSFET comprising a conductive contact to the upper surface of the common substrate arranged to contact a second source region of semiconductor material of said first conductivity type extending from the upper surface into the second well, the drain of the second MOSFET comprising a conductive contact to the upper surface of the common substrate arranged to contact a drain region of semiconductor material of said first conductivity type extending from the upper surface into the second well, and wherein the second body region of the second MOSFET comprises at least part of said second well, and wherein the first well is formed within an off state depletion region of the first MOSFET, and the second well is formed outside the off state depletion region of the first MOSFET.
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Specification