Acoustic wave resonator with integrated temperature control for oscillator purposes
The present invention relates to a resonator structure, temperature compensation method and temperature control apparatus for controlling local temperature of a resonator structure. At least one heating element ( 55 ) is integrated on a substrate of the resonator structure, and a temperature control signal generated based on a stored temperature characteristic is applied to the at least one integrated heating element ( 55 ). Thereby, the at least one heating element ( 55 ) and an optional integrated sensing element can be provided very close to the resonator. It is thus possible to control or calibrate variations of sensing elements, heating elements and resonator out from every sample.
1. A resonator structure integrated on a substrate and comprising:
a) an acoustically active part;
b) first and second electrodes arranged on opposite sides of said acoustically active part; and
c) at least one controllable heating element integrated on said substrate, configured to supply heat to said resonator structure and configured to be controlled based on sampling points gathered by a frequency calibration and stored in a memory.
2. A resonator structure according to claim 1 , wherein said controllable heating element is configured to be used as a temperature sensing element for sensing local temperature of said resonator structure.
3. A resonator structure according to claim 1 , further comprising a temperature sensing element integrated on said substrate and configured to sense local temperature of said resonator structure.
4. A resonator structure according to claim 3 , wherein said temperature sensing element comprises at least one doped region of said substrate.
5. A resonator structure according to claim 1 , wherein said at least one controllable heating element comprises at least one doped region of said substrate.
6. A resonator structure according to claim 1 , wherein said at least one controllable heating element comprises at least one metal strip pattern integrated on said substrate.
7. A resonator structure according to claim 1 , wherein said resonator structure is a bulk acoustic wave resonator structure or a surface acoustic wave resonator structure.
8. A mobile phone device comprising reference oscillator means with a resonator structure as claimed in claim 1 .