A mechanically tunable GHz passive voltage element using microstrip resonator

The ability to detect very low RF signals can be used to wake-up a sensor node only when needed to sense or transmit data, reducing the sensor node power consumption. A passive voltage transforming stage from the antenna to a nano-watt receiver can be useful to reduce the minimum detectable RF signal. At high RF frequencies, the transformer is harder to implement owing to the low impedance of load capacitive loads. We demonstrate a gigahertz frequency range passive voltage transformer, using a mechanically tunable strip-line resonator at 1-2 GHz. The transformer exhibited a 19.5dB gain at 1.007 GHz and achieved gains over 19dB with load capacitances of 0.8-2.4pF. A piezoelectric AlN GHz transducer was also used to measure the gain of the resonator. An RF waveguide model has been developed which matches experiments well for both frequency and gain responses.