Back to results
US 12,742,806 B2Granted
Capacitance sensing circuit
AssigneeNXP B.V.
InventorGeunwook Kim
Life of this patent
Estimating the term…
Abstract
A capacitance sensing circuit and method uses a current pulse to charge an external capacitor. A first voltage associated with the external capacitor is converted to current to charge an internal capacitor. A second voltage, which is associated with the internal capacitor that corresponds to the first voltage, is compared with an adjustable threshold voltage to generate a toggle signal. The adjustable threshold voltage is changed in response to the toggle signal, which is associated with a capacitance of the external capacitor.
Claims20
A capacitance sensing circuit comprising:
- a current pulse generator configured to generate a current pulse to charge an external capacitor;
- a voltage-to-current converter to convert a first voltage associated with the external capacitor to current to charge an internal capacitor;
- a comparator operably connected to the internal capacitor to generate a toggle signal when a second voltage corresponding to the first voltage reaches an adjustable threshold voltage;
- and
- a processing unit operably connected to the comparator to change the adjustable threshold voltage in response to the toggle signal generated by the comparator, wherein the toggle signal is associated with a capacitance of the external capacitor.
2 more elements
A method comprising:
- generating a current pulse to charge an external capacitor;
- converting a first voltage associated with the external capacitor to current to charge an internal capacitor;
- comparing a second voltage with an adjustable threshold voltage to generate a toggle signal, the second voltage being associated with the internal capacitor that corresponds to the first voltage;
- and changing the adjustable threshold voltage in response to the toggle signal, wherein the toggle signal is associated with a capacitance of the external capacitor.
1 more element
A capacitance sensing circuit comprising:
- a current pulse generator configured to generate a current pulse to charge an external capacitor;
- a voltage-to-current converter to convert a first voltage associated with the external capacitor to current to charge an internal capacitor;
- a comparator operably connected to the internal capacitor to generate a toggle signal when a second voltage corresponding to the first voltage reaches an adjustable threshold voltage;
- a resistor ladder connected to the comparator via switches to provide the adjustable threshold voltage;
- and
- a switch controller operably connected to the switches to provide signals to the switches to control the adjustable threshold voltage based on the toggle signal, wherein the toggle signal is associated with a capacitance of the external capacitor.
3 more elements
Dependencies are inferred from the claim text.