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US 7,403,147 B2Granted
Precision capacitor array
AssigneeSiTime Corporation
InventorErno H. Klaassen
Life of this patent
Estimating the term…
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.
Claims16
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.
2 more elements
A frequency reference comprising:
- 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.
4 more elements
A capacitor array comprising:
- 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.
Dependencies are inferred from the claim text.