Successive approximate capacitance measurement circuit
First Claim
Patent Images
1. A capacitance measurement circuit, comprising:
- a variable current source coupled to drive a selectable current through a circuit node;
a switch coupled to the circuit node to switch the selectable current into a device under test (“
DUT”
) capacitor;
a comparator including first and second input ports, the comparator coupled to compare a first voltage to be received on the first input port against a reference voltage to be received on the second input port and generate an output signal in response, wherein the first voltage is related to the selectable current driven through the circuit node, a switching frequency at which the switch is switched, and a capacitance of the DUT capacitor, wherein the switch is coupled between the first input port of the comparator and the DUT capacitor; and
capacitance measurement logic coupled to receive the output signal from the comparator and coupled to adjust at least one of the switching frequency or a magnitude of the selectable current dependent upon the output signal.
6 Assignments
0 Petitions
Accused Products
Abstract
A capacitance measurement circuit includes a current source, a switch, and a comparator. The current source is coupled to drive a current through a circuit node. The switch is coupled to the circuit node to switch the current into a device under test (“DUT”) capacitor. The comparator includes first and second input ports. The comparator is coupled to compare a first voltage received on the first input port against a reference voltage received on the second input port. The first voltage is related to the current driven through the circuit node, a frequency at which the switch is switched, and a capacitance of the DUT capacitor.
276 Citations
19 Claims
-
1. A capacitance measurement circuit, comprising:
-
a variable current source coupled to drive a selectable current through a circuit node; a switch coupled to the circuit node to switch the selectable current into a device under test (“
DUT”
) capacitor;a comparator including first and second input ports, the comparator coupled to compare a first voltage to be received on the first input port against a reference voltage to be received on the second input port and generate an output signal in response, wherein the first voltage is related to the selectable current driven through the circuit node, a switching frequency at which the switch is switched, and a capacitance of the DUT capacitor, wherein the switch is coupled between the first input port of the comparator and the DUT capacitor; and capacitance measurement logic coupled to receive the output signal from the comparator and coupled to adjust at least one of the switching frequency or a magnitude of the selectable current dependent upon the output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. An apparatus, comprising:
-
a source of current coupled to drive current through a circuit node; a first switch coupled to switch the current into a device under test (“
DUT”
) capacitor;a second switch coupled to selectively discharge the DUT capacitor; a comparator including first and second ports, the first port of the comparator coupled to the circuit node independent of whether the second switch is open circuited, the comparator coupled to compare a first voltage to be received on the first port against a second voltage to be received on the second port and generate an output signal in response, wherein a change in the first voltage is related to a change in a capacitance of the DUT capacitor, wherein the first switch is coupled between the first input port of the comparator and the DUT capacitor; and capacitance measurement logic coupled to receive the output signal from the comparator and coupled to adjust at least one of a switching frequency of the first switch or a magnitude of the current dependent upon the output signal. - View Dependent Claims (13, 14, 15, 16)
-
-
17. A machine-accessible storage medium having embodied thereon a description of an integrated circuit, the integrated circuit comprising:
-
a current source coupled to drive a current through a circuit node; a first switch coupled between the circuit node and a device under test (“
DUT”
) capacitor to switch the current into the DUT capacitor;a second switch coupled to selectively discharge the DUT capacitor when the first switch is open circuited; a comparator including first and second input ports, the comparator electrically coupled to the circuit node independent of whether the second switch is open circuited, the comparator to compare a first voltage to be received on the first input port against a reference voltage to be received on the second input port and generate an output signal in response, wherein the first voltage is related to the current driven through the circuit node, a switching frequency at which the switch is switched, and a capacitance of the DUT capacitor; and capacitance measurement logic coupled to receive the output signal from the comparator and coupled to adjust at least one of the switching frequency or a magnitude of the current dependent upon the output signal. - View Dependent Claims (18, 19)
-
Specification