Method of reading a capacitive sensor and related integrated circuit
First Claim
1. A method of reading a capacitive pressure sensor comprising an array of pressure-sensing capacitors ordered in rows and columns functionally connected through row lines and through column lines substantially orthogonal to each other, using a biasing and reading circuit comprising column and row selectors, and a charge amplifier outputting a voltage of the pressure based capacitance of a selected pressure-sensing capacitor of the array, the method comprising:
- resetting an output voltage of the charge amplifier;
connecting nonselected row and column lines of the array to a reference voltage while connecting one of an auxiliary capacitor and the selected pressure-sensing capacitor to an input of the amplifier while connecting the other one of the auxiliary capacitor and the selected pressure-sensing capacitor to define a feedback capacitor of the amplifier, the feedback capacitor being discharged by the connection of the nonselected row and column lines of the array to the reference voltage; and
applying a step voltage on the one of the auxiliary capacitor and the selected pressure-sensing capacitor that is connected to the input of the amplifier and reading the output voltage at steady-state.
1 Assignment
0 Petitions
Accused Products
Abstract
The method is for reading a capacitive sensor and may be implemented by a circuit for biasing and reading capacitances that includes circuits for selecting a column line and a row line, and a charge amplifier producing an output voltage representing the capacitance of the selected capacitor intercepted by the selected column and row lines. The method includes preliminarily resetting the output voltage of the charge amplifier, connecting all the deselected row and column plates of the array to a reference voltage and connecting a feedback capacitor and the selected capacitor to an inverting input of the amplifier, applying a step voltage on the capacitor that is connected to the inverting input of the amplifier, and reading the output voltage at steady-state.
33 Citations
17 Claims
-
1. A method of reading a capacitive pressure sensor comprising an array of pressure-sensing capacitors ordered in rows and columns functionally connected through row lines and through column lines substantially orthogonal to each other, using a biasing and reading circuit comprising column and row selectors, and a charge amplifier outputting a voltage of the pressure based capacitance of a selected pressure-sensing capacitor of the array, the method comprising:
-
resetting an output voltage of the charge amplifier; connecting nonselected row and column lines of the array to a reference voltage while connecting one of an auxiliary capacitor and the selected pressure-sensing capacitor to an input of the amplifier while connecting the other one of the auxiliary capacitor and the selected pressure-sensing capacitor to define a feedback capacitor of the amplifier, the feedback capacitor being discharged by the connection of the nonselected row and column lines of the array to the reference voltage; and applying a step voltage on the one of the auxiliary capacitor and the selected pressure-sensing capacitor that is connected to the input of the amplifier and reading the output voltage at steady-state. - View Dependent Claims (2, 3)
-
-
4. A method of reading a capacitive pressure sensor comprising an array of pressure-sensing capacitors connected in rows and columns, the method comprising:
-
providing a biasing and reading circuit comprising column and row selectors, an amplifier, connected to the column and row selectors, for outputting a voltage of the pressure based capacitance of a selected pressure-sensing capacitor of the array, and an auxiliary capacitor connected to the column and row selectors; connecting nonselected rows and columns of the array to a reference voltage while connecting one of the auxiliary capacitor and the selected pressure-sensing capacitor as an input of the amplifier while connecting the other one of the auxiliary capacitor and the selected pressure-sensing capacitor to define a feedback capacitor of the amplifier, the feedback capacitor being discharged by the connection of the nonselected row and column lines of the array to the reference voltage; and applying a step voltage on the one of the auxiliary capacitor and the selected pressure-sensing capacitor that is connected on the input of the amplifier and reading the output voltage at steady-state. - View Dependent Claims (5, 6, 7)
-
-
8. A system for reading a capacitive pressure sensor comprising an array of pressure-sensing capacitors connected in rows and columns, the system comprising:
-
a biasing and reading circuit comprising an amplifier for outputting a voltage representing the pressure based capacitance of a selected pressure-sensing capacitor, an auxiliary capacitor, configuration switches for coupling one of the auxiliary capacitor and the selected pressure-sensing capacitor as a feedback capacitor and for coupling the other of the auxiliary capacitor and the selected pressure-sensing capacitor to an input of the amplifier, and an analog-to-digital converter for converting the output voltage to digital data; an input interface circuit for connecting deselected row lines and column lines of the array to a reference voltage and while coupling the selected pressure-sensing capacitor of the capacitive pressure sensor to the biasing and reading circuit, the feedback capacitor being discharged by the connection of the deselected row and column lines of the array to the reference voltage; a microprocessor for performing noise filtering and real-time correction of data; and a digital output interface circuit controlled by the microprocessor for outputting the digital data representing read values of capacitance of the capacitive pressure sensor. - View Dependent Claims (9, 10, 11)
-
-
12. An integrated circuit for reading a capacitive pressure sensor comprising an array of pressure-sensing capacitors connected in rows and columns, the circuit comprising:
-
column and row selectors; an amplifier, connected to the column and row selectors, for outputting a voltage of the pressured-based capacitance of a selected pressure-sensing capacitor of the array; an auxiliary capacitor connected to the column and row selectors; configuration switches for connecting deselected row lines and column lines of the array to a reference voltage and while coupling one of the auxiliary capacitor and the selected pressure-sensing capacitor as a feedback capacitor and for coupling the other of the auxiliary capacitor and the selected pressure-sensing capacitor to an input of the amplifier, the feedback capacitor being discharged by the connection of the deselected row and column lines of the array to the reference voltage; and a controller for controlling the configuration switches. - View Dependent Claims (13, 14)
-
-
15. A capacitive pressure sensor device comprising:
-
an array of pressure-sensing capacitors connected in rows and columns; and a reading circuit for reading the array of pressure-sensing capacitors and comprising column and row selectors, an amplifier, connected to the column and row selectors, for outputting a voltage of the pressure-based capacitance of a selected pressure-sensing capacitor of the array, an auxiliary capacitor connected to the column and row selectors, configuration switches for connecting deselected row lines and column lines of the array to a reference voltage and while coupling one of the auxiliary capacitor and the selected pressure-sensing capacitor as a feedback capacitor and for coupling the other of the auxiliary capacitor and the selected pressure-sensing capacitor to an input of the amplifier, the feedback capacitor being discharged by the connection of the deselected row and column lines of the array to the reference voltage, and a controller for controlling the configuration switches. - View Dependent Claims (16, 17)
-
Specification