Monolithic voltage divider
First Claim
Patent Images
1. A monolithic integrated circuit for dividing the voltage supplied by a power supply comprising:
- a plurality of capacitors wherein one of the capacitors is a reference capacitor;
switching means for periodically coupling at least two of the capacitors in series to the power supply during a first time period and for periodically coupling at least two of the capacitors in parallel during a second time period such that the voltage across one of the capacitors provides a reference voltage which approaches a predetermined fraction of the supply voltage of the power supply; and
a voltage regulator having an input operably connected to the capacitor providing the reference voltage, and an output which provides a supply voltage at the predetermined fraction of the power supply, said voltage regulator having an input impedance in excess of 10 megohms to minimize loading of the capacitors.
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Abstract
A voltage divider circuit is provided which can be fabricated as a portion of a monolithic integrated circuit without requiring any external capacitors. The voltage divider circuit has a pair of capacitors which are alternately switched between series connection and parallel connection to divide an input supply voltage. The voltage divider circuit can thereby provide a second supply voltage of one half the input supply voltage.
32 Citations
20 Claims
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1. A monolithic integrated circuit for dividing the voltage supplied by a power supply comprising:
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a plurality of capacitors wherein one of the capacitors is a reference capacitor; switching means for periodically coupling at least two of the capacitors in series to the power supply during a first time period and for periodically coupling at least two of the capacitors in parallel during a second time period such that the voltage across one of the capacitors provides a reference voltage which approaches a predetermined fraction of the supply voltage of the power supply; and a voltage regulator having an input operably connected to the capacitor providing the reference voltage, and an output which provides a supply voltage at the predetermined fraction of the power supply, said voltage regulator having an input impedance in excess of 10 megohms to minimize loading of the capacitors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A monolithic integrated circuit for dividing the voltage supplied by a power supply comprising:
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first and second capacitors; switching means for cyclically connecting the capacitors in series to the power supply during a first time period and for cyclically connecting the capacitors in parallel during a second time period such that the voltage across one of the capacitors provides a reference voltage which approaches a predetermined fraction of the supply voltage of the power supply; and a voltage regulator which includes a CMOS differential amplifier and a buffer driver transistor, said amplifier having an input operably connected to the capacitor providing the reference voltage and an output operably connected to the driver transistor, said regulator being responsive to the reference voltage for providing a regulated output from the driver transistor, and said amplifier input having a sufficiently large input impedance such that the capacitors may be small enough for practical fabrication as a portion of the monolithic integrated circuit.
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13. A monolithic integrated circuit for dividing the voltage supplied by a power supply by a third, comprising:
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first, second, and third capacitors wherein the third capacitors is a reference capacitor; switching means for periodically coupling the capacitors in series to the power supply during a first and a third time period, for coupling the first and second capacitors in parallel during a second time period and for coupling the second and reference capacitors in parallel during a fourth time period such that the voltage across the reference capacitor provides a reference voltage which approaches one-third of the supply voltage of the power supply; and a voltage regulator having an input operably connected to the reference capacitor and an output which provides a supply voltage at one-third of the power supply voltage, said voltage regulator having an input impedance in excess of 10 megohms to minimize loading of the capacitors by the regulator.
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14. A monolithic integrated circuit for dividing the voltage supplied by a power supply by a third, comprising:
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first, second, third and fourth capacitors wherein the fourth capacitor is a reference capacitor; switching means for periodically coupling the second and third capacitors in parallel and the parallel combination of the second and third capacitors in series with the first and reference capacitors to the power supply during a first time period and for coupling the first and second capacitors in parallel and the third and reference capacitors in parallel during a second time period such that the voltage across the reference capacitor provides a reference voltage which approaches one-third of the supply voltage of the power supply; and a voltage regulator having an input operably connected to the reference capacitor and an output which provides a supply voltage at one-third of the power supply voltage, said voltage regulator having an input impedance in excess of 10 megohms to minimize loading of the capacitors by the regulator.
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15. A monolithic integrated circuit for dividing the voltage supplied by a power supply comprising:
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a plurality of capacitors wherein one of the capacitors is a reference capacitor; switching means for periodically coupling the capacitors in series to the power supply during a first time period and for alternately coupling one or more pairs of capacitors in parallel during one or more intervening time periods such that the voltage across each capacitor approaches the same voltage wherein the voltage across the reference capacitor provides a reference voltage of the power supply determined by the number of capacitors coupled in series to the power supply during the first time period; and a voltage regulator having an input operably connected to the reference capacitor and an output which provides a supply voltage at the predetermined fraction of the power supply, said voltage regulator having an input impedance in excess of 10 megohms to minimize loading of the capacitors by the regulator.
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16. A monolithic integrated circuit for dividing the voltage supplied by a power supply comprising:
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a plurality of capacitors wherein one of the capacitors is a reference capacitor; switching means for periodically connecting the capacitors in series to the power supply during a first time period and for connecting a capacitor in parallel with the reference capacitor during a second time period such that the voltage across the reference capacitor provides a reference voltage which approaches a predetermined fraction of the supply voltage of the power supply; and a voltage regulator which includes a differential amplifier having an input transistor which has a gate operably connected to the reference capacitor, said transistor having an input impedance in excess of 10 megohms to minimize loading of the capacitors by the regulator, said regulator having an output which provides a supply voltage at the predetermined fraction of the power supply.
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17. A monolithic integrated circuit for dividing the voltage supplied by a power supply comprising:
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a plurality of capacitors wherein one of the capacitors is a reference capacitor; switching means for periodically connecting the capacitors in series to the power supply during a first time period and for connecting a capacitor in parallel with the reference capacitor during a second time period such that the voltage across the reference capacitor provides a reference voltage which approaches a predetermined fraction of the supply voltage of the power supply; and a voltage regulator having an input operably connected to the reference capacitor and an output which provides a supply voltage at the predetermined fraction of the power supply, said voltage regulator having an extremely high input impedance to minimize loading of the capacitors by the regulator, said regulator including a buffer driver for operable connection to a load, said buffer driver to buffer the capacitors from the load to prevent loading of the capacitors by the load.
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18. A monolithic integrated circuit chip for multiplying the supply voltage supplied by a power supply by a predetermined factor comprising:
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a plurality of capacitors disposed on the chip; switching means for cyclicly coupling at least two of the capacitors in series to the power supply during a first time period and for cyclicly coupling at least two of the capacitors in parallel during a second time period so that at least one of the capacitors provides a reference voltage; and a voltage regulator having an input operably connected to the capacitor providing the reference voltage, said regulator being responsive to the reference voltage for providing a regulated output at a voltage level which is equal to the supply voltage multiplied by the predetermined factor, and said regulator input having a sufficiently large input impedance such that the capacitors may be small enough for practical fabrication as a portion of the monolithic integrated circuit. - View Dependent Claims (19)
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20. A monolithic integrated circuit for dividing the voltage supplied by a power supply and driving a load, comprising:
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first and second capacitors; switching means for cyclicly coupling the capacitors in series to the power supply during a first time period and for cyclicly coupling the capacitors in parallel during a second time period so that the voltage across one of the capacitors provides a reference voltage which approaches a predetermined fraction of the supply voltage of the power supply; and a voltage regulator having an input operably connected to the capacitor providing the reference voltage, and a buffer driver to buffer the capacitors from the load to prevent loading of the capacitors by the load, said regulator being responsive to the reference voltage for providing a regulated output from the buffer driver.
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Specification