Metal Bulk Foil Resistor Characterization for BAW Application at Low Cryogenic Temperatures

We report on the development of a characterization system and calibration procedure for a bulk acoustic wave (BAW) resonator using a bulk metal foil resistor operated at temperatures as low as tens of millikelvin. The 50-Ω resistor demonstrated extremely good stability and small drift at a temperature of 50 mK, with the resistance varying by 1.5% between room temperature and 50 mK. The BAW quartz resonator exhibited a quality factor of 8×10
⁵
at 206 MHz, which is one order of magnitude higher than state-of-the-art equivalent devices at ambient temperature. Such results were obtained due to the combination of a suitable technology of resistor, and the custom design of an electronic circuit board for calibration.