SENSOR DEVICE WITH REDUCED PARASITIC-INDUCED ERROR
First Claim
1. A device comprising:
- a sensor element having a first drive node and a first sense node, wherein a first parasitic current is present between said first drive node and said first sense node when a drive signal is applied at said first drive node; and
a capacitive network having a first input coupled to a voltage source and a first output coupled to said first sense node, said first capacitive network substantially canceling said first parasitic current when a second drive signal of opposite phase to said first drive signal is applied at said first input.
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Accused Products
Abstract
A device (110) includes a sensing element (26) having drive nodes (34, 36) and sense nodes (42, 44). Parasitic capacitance (22) is present between drive node (34) and sense node (42). Likewise, parasitic capacitance (24) is present between drive node (36) and sense node (44). When a drive signal (56) is applied between drive nodes (34, 36), a parasitic current (70) between drive and sense nodes (34, 42) and a parasitic current (72) between drive and sense nodes (36,44) is created due to the parasitic capacitances (22, 24). A capacitive network (112) is coupled between the drive node (36) and the sense node (42) to create a correction current (134) through capacitive network (112) that cancels parasitic current (70). Likewise, a capacitive network (114) is coupled between the drive node (34) and the sense node (44) to create a correction current (138) through capacitive network (112) that cancels parasitic current (72).
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Citations
20 Claims
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1. A device comprising:
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a sensor element having a first drive node and a first sense node, wherein a first parasitic current is present between said first drive node and said first sense node when a drive signal is applied at said first drive node; and a capacitive network having a first input coupled to a voltage source and a first output coupled to said first sense node, said first capacitive network substantially canceling said first parasitic current when a second drive signal of opposite phase to said first drive signal is applied at said first input. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of substantially cancelling parasitic current in a device, said device including a sensor element having a first drive node, a second drive node, a first sense node, and a second sense node, a first capacitive network having a first input coupled to said second drive node and a first output coupled to said first sense node, a second capacitive network having a second input coupled to said first drive node and a second output coupled to said second sense node, and said method comprising:
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adjusting said first capacitive network to provide a first effective capacitance that is substantially equivalent to a first determined parasitic capacitance between said first drive node and said first sense node, said first parasitic capacitance causing a first parasitic current upon application of a drive signal to said sensor element; adjusting said second capacitive network to provide a second effective capacitance that is substantially equivalent to a second determined parasitic capacitance between said second drive node and said second sense node, said second parasitic capacitance causing a second parasitic current upon application of said drive signal to said sensor element; and applying said drive signal at said first and second drive nodes to drive said sensor element, said drive signal concurrently being applied to said first and second capacitive networks to form a first correction current through said first capacitive network that is substantially equivalent and opposite in phase to said first parasitic current and to form a second correction current through said second capacitive network that is substantially equivalent and opposite in phase to said second parasitic current such that said first and second parasitic currents are substantially cancelled. - View Dependent Claims (16, 17, 18)
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19. A device comprising:
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a resonator element having a first drive node, a second drive node, a first sense node, and a second sense node, wherein a first parasitic capacitance is present between said first drive node and said first sense node to produce a first parasitic current, a second parasitic capacitance is present between said second drive node and said second sense node to produce a second parasitic current between said second drive node and said second sense node, said first and second parasitic currents being present when a drive signal is applied between said first and second drive nodes; a first capacitive network including multiple first capacitive circuits connected in parallel to produce a first effective capacitance that is substantially equivalent to said first parasitic capacitance, said first capacitive network having a first input connected to said second drive node and having a first output connected to said first sense node, said first capacitive network forming a first correction current when said drive signal is applied between said first and second drive nodes that is substantially equivalent and opposite in phase to said first parasitic current to substantially cancel said first parasitic current; and a second capacitive network including multiple second capacitive circuits connected in parallel to produce a second effective capacitance that is substantially equivalent to said second parasitic capacitance, said second capacitive network having a second input connected to said first drive node and a second output connected to said second sense node, said second capacitive network forming a second correction current when said drive signal is applied between said first and second drive nodes that is substantially equivalent and opposite in phase to said second parasitic current to substantially cancel said second parasitic current. - View Dependent Claims (20)
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Specification