Thermally driven thin film bulk acoustic resonator voltage controlled oscillators integrated with microheater elements

Abstract

In this letter, we report on thermally driven thin film bulk acoustic resonator (TFBAR) voltage-controlled oscillators (VCOs) integrated with a microheater element. The oscillation frequency of TFBAR VCOs is controlled by applying different power (or bias voltage) to the microheaters implemented on the TFBAR membrane. The TFBARs with the microheater elements are fabricated by Si bulk micromachining technology. The series feedback schematic TFBAR VCO has an oscillation frequency of 3.566 GHz, an output power of -21 dBm, and a phase noise of -110 dBc/Hz at an offset frequency of 100 kHz. The measured frequency controllability and the measured temperature coefficient of resistance (TCR) of the heater element are 3.19 MHz/V and 0.24%/degreesC, respectively, with a resistance of 88.1 Omega at room temperature.