Hypersonic generator for SAW gas sensors

Commercially available surface acoustic wave (SAW) sensors usually work within the frequency range from a few dozen to a few hundred MHz. It is well-known that the mass sensitivity of a SAW sensor is directly proportional to its operating frequency and many SAW sensors are mass sensitive. For this reason, designers are still looking for high frequency generators for SAW sensors. The design of a hypersonic generator with a SAW resonator is described. The circuit works stably at 4.710 GHz (29^th harmonic of the loaded resonator) at the -2.35 dBm level. In the construction, distributed-parameter circuits have been applied. The generator can be used in high sensitivity SAW sensors for the detection of complex organic gases and vapours.