Testing circuit and method for MEMS sensor packaged with an integrated circuit
First Claim
Patent Images
1. A packaged device comprising:
- a micro-electromechanical systems (MEMS) sensor comprising a moving element connected to a first output, a first plate connected to a second output and a second plate connected to a third output, wherein the moving element and the first plate form a first capacitor producing a first capacitance and the moving element and the second plate form a second capacitor producing a second capacitance;
an amplifier with a first input connected to the first output, a second input connected to a first voltage of a plurality of voltages and a fourth output accessible outside the integrated circuit;
a testing means for causing an output voltage appearing at the fourth output to reflect one of the first and the second capacitances, wherein the testing means comprises a first switch preventing any voltage from being applied to the second output in an open state.
19 Assignments
0 Petitions
Accused Products
Abstract
A MEMS sensor packaged with an integrated circuit includes switches and control circuitry. In a test mode, the control circuitry causes the switches to turn off and on such that the first and second capacitance of the MEMS sensor can be monitored individually. During a normal mode of operation, the switches are maintained such that the MEMS sensor packaged with the integrated circuit operates to produce a filtered and trimmed output reflecting the sensed phenomena.
40 Citations
15 Claims
-
1. A packaged device comprising:
-
a micro-electromechanical systems (MEMS) sensor comprising a moving element connected to a first output, a first plate connected to a second output and a second plate connected to a third output, wherein the moving element and the first plate form a first capacitor producing a first capacitance and the moving element and the second plate form a second capacitor producing a second capacitance;
an amplifier with a first input connected to the first output, a second input connected to a first voltage of a plurality of voltages and a fourth output accessible outside the integrated circuit;
a testing means for causing an output voltage appearing at the fourth output to reflect one of the first and the second capacitances, wherein the testing means comprises a first switch preventing any voltage from being applied to the second output in an open state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A packaged device comprising:
-
a micro-electromechanical systems (MEMS) sensor comprising a moving element connected to a first output, a first plate connected to a second output and a second plate connected to a third output, wherein the moving element and the first plate form a first capacitor producing a first capacitance and the moving element and the second plate form a second capacitor producing a second capacitance;
an amplifier with a first input connected to the first output, a second input connected to a first voltage of a plurality of voltages and a fourth output accessible outside the integrated circuit;
a reference capacitor connected between the first input and the fourth output;
a control logic providing a plurality of control signals;
a first switch connected between the second output and the control logic, wherein the switch is enabled or disabled by a first control signal of the plurality of control signals;
a second switch connected between the third output and the control logic, wherein the second switch is enabled or disabled by a second control signal of the plurality of control signals; and
a third switch connected between the first input and the fourth output, wherein the third switch is enabled or disabled by a third control signal of the plurality of control signals. - View Dependent Claims (13, 14)
-
-
15. A method for testing individual characteristics of a first capacitance and a second capacitance of a micro-electromechanical systems (MEMS) sensor packaged with an integrated circuit comprising:
-
disabling one of either the first capacitance and the second capacitance;
causing a common node of the first and second capacitance to appear on a first input of an amplifier;
causing a reference voltage to appear on a second input of the amplifier;
discharging a reference capacitor connected between the first input and an output of the amplifier;
after discharging the reference capacitor causing a voltage applied to the other of either the first capacitance and the second capacitance to change from the reference voltage to an excitation voltage;
measuring a characteristic representative of the other of either the first capacitance and the second capacitance appearing on the output; and
intermittently discharging the reference capacitor and causing the voltage applied to the other of the first capacitance and second capacitance to step between the reference voltage and the excitation voltage.
-
Specification