Precision capacitor array
First Claim
Patent Images
1. A capacitor array comprising:
- a plurality of unit capacitors addressed with a monotonic combination binary-thermometer coded addressing scheme and comprising binary coded capacitor groups and thermometer coded capacitor groups, wherein;
the unit capacitors are arranged in a common-centroid layout;
the binary coded capacitor groups are located closer to the center of the common-centroid layout than the thermometer coded capacitor groups; and
each unit capacitor is electrically shielded from one or more neighbor capacitors.
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Abstract
A digital capacitor array with individually shielded unit capacitors and combination binary—thermometer coded addressing is disclosed. Such a capacitor array may be part of a digitally controlled oscillator in a MEMS-based frequency reference.
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Citations
16 Claims
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1. A capacitor array comprising:
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a plurality of unit capacitors addressed with a monotonic combination binary-thermometer coded addressing scheme and comprising binary coded capacitor groups and thermometer coded capacitor groups, wherein; the unit capacitors are arranged in a common-centroid layout; the binary coded capacitor groups are located closer to the center of the common-centroid layout than the thermometer coded capacitor groups; and each unit capacitor is electrically shielded from one or more neighbor capacitors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A frequency reference comprising:
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a MEMS resonator with digital signal extraction circuits; and
,a digitally controlled oscillator comprising a capacitor array which comprises a plurality of unit capacitors addressed by a monotonic combination binary—
thermometer coded addressing scheme and comprising binary coded capacitor groups and thermometer coded capacitor groups, wherein;the unit capacitors are arranged in a common-centroid layout, the binary coded capacitor groups are located closer to the center of the common-centroid layout than the thermometer coded capacitor groups, each unit capacitor is electrically shielded from one or more neighbor capacitors and from array address lines and, each unit capacitor comprises two plates wherein an electrical connection to one of the plates is made through a hole in the other. - View Dependent Claims (12)
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13. A capacitor array comprising:
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a plurality of unit capacitors arranged in a common-centroid layout and connected to address lines that connect combinations of capacitors to form an array capacitance according to a digital code, wherein the common-centroid layout comprises binary coded groups of unit capacitors and thermometer coded groups of unit capacitors, wherein; the binary coded capacitor groups are located closer to the center of the common-centroid layout than the thermometer coded capacitor groups, and the number of bits representing the binary coded capacitor groups is chosen such that a monotonic increase in array capacitance with digital code is achieved. - View Dependent Claims (14, 15, 16)
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Specification