On-chip hotplate for temperature control of CMOS SAW resonators

Due to the sensitivity of the piezoelectric layer in surface acoustic wave (SAW) resonators to temperature, a method of achieving device stability as a function of temperature is required. This work presents the design, modeling and characterization of integrated dual-serpentine polysilicon resistors as a method of temperature control for CMOS SAW resonators. The design employs the oven control temperature stabilization scheme where the devicepsilas temperature is elevated to higher than T
_max
to maintain constant device temperature. The efficiency of the polysilicon resistor as a heating element was verified through a 1-D partial differential equation model, 3-D CoventorWarereg finite element simulations and measurements using Compixreg thermal camera. To verify that the on-chip hotplate is effective as a temperature control method, both DC and RF measurements of the heater together with the resonator were conducted. Experimental results have indicated that the TCF of the CMOS SAW resonator of -97.2 ppm/degC has been reduced to -23.19 ppm/degC when heated to 56degC.