Aging compensation of a ferroelectric piezoelectric shock sensor

1. A method comprising:

measuring a temperature of a semiconductor die, in which the semiconductor die includes a piezoelectric device, a pyroelectric device, and a memory;

receiving a signal from the pyroelectric device;

based on the signal and the temperature, determining a calibration parameter of the piezoelectric device; and

storing the calibration parameter into the memory.

2. The method of claim 1 , further comprising heating the semiconductor die to a predetermined temperature in an oven.

3. The method of claim 1 , wherein the temperature is a first temperature, the signal is a first signal, and the semiconductor die includes a heater and a temperature sensor; and

wherein the method further comprises:

heating the pyroelectric device by the heater;

receiving a second signal from the heated pyroelectric device;

measuring a second temperature of the pyroelectric device by the temperature sensor;

determining a relationship between pyroelectric signal and temperature based on the first and second temperatures and the first and second signals; and

determining calibration parameter based on the relationship.

4. The method of claim 3 , wherein the calibration parameter includes a scaling factor that represents a drift of the piezoelectric device due to temperature.

5. The method of claim 3 , wherein the heater includes a resistor;

wherein the pyroelectric device is heated by passing a first voltage across the resistor; and

wherein the first and second temperatures are measured by measuring respective second and third voltages across the resistor.

6. The method of claim 1 , further comprising poling the pyroelectric device before receiving the signal.

7. The method of claim 6 , wherein:

the pyroelectric device includes a set of serially-connected pyroelectric capacitors; and

the poling of the pyroelectric device includes successively connecting each one of a set of poling signal sources to a respective one of the set of pyroelectric capacitors in a first sequence, and successively disconnecting each one of the set of poling signal sources from a respective one of the set of pyroelectric capacitors in a second sequence reversed from the first sequence.

8. The method of claim 7 , wherein the semiconductor die includes the set of poling signal sources.

9. The method of claim 1 , wherein the signal is a first signal, the calibration parameter is a first calibration parameter, and the method further comprises:

receiving a second signal when the semiconductor die is at a particular acceleration;

determining a second calibration parameter that relates the second signal to the particular acceleration and the temperature; and

storing the second calibration parameter in the memory.

10. The method of claim 9 , further comprising poling the piezoelectric device before receiving the second signal.

11. The method of claim 10 , wherein:

the piezoelectric device includes a set of serially-connected piezoelectric capacitors; and

the poling of the piezoelectric device includes successively connecting each one of a set of poling signal sources to a respective one of the set of piezoelectric capacitors in a first sequence, and successively disconnecting each one of the set of poling signal sources from a respective one of the set of piezoelectric capacitors in a second sequence reversed from the first sequence.

12. A semiconductor die, comprising:

a piezoelectric device;

a pyroelectric device;

a temperature sensor;

a memory; and

a control circuit coupled to the piezoelectric device, pyroelectric device, temperature sensor, and the memory, the control circuit configured to:

receive a measurement of a temperature of the semiconductor die from the temperature sensor;

receive a signal from the pyroelectric device;

based on the first signal and the temperature, determine a calibration parameter of the piezoelectric device; and

store the calibration parameter into the memory.

13. The semiconductor die of claim 12 , further comprising a heater coupled to the control circuit.

14. The semiconductor die of claim 12 , wherein the pyroelectric device includes a set of serially-connected pyroelectric capacitors, and the semiconductor die further comprises a set of poling signal sources;

wherein the control circuit is configured to pole the pyroelectric device by successively connecting each one of the set of poling signal sources to a respective one of the set of pyroelectric capacitors in a first sequence, and successively disconnecting each one of the set of poling signal sources from a respective one of the set of pyroelectric capacitors in a second sequence reversed from the first sequence.

15. The semiconductor die of claim 12 , wherein the piezoelectric device includes a set of serially-connected piezoelectric capacitors; and

wherein the control circuit is configured to pole the piezoelectric device by successively connecting each one of a set of poling signal sources to a respective one of the set of piezoelectric capacitors in a first sequence, and successively disconnecting each one of the set of poling signal sources from a respective one of the set of piezoelectric capacitors in a second sequence reversed from the first sequence.