Abstract :
A design of an overtone oscillator a with surface-acoustic-wave (SAW) resonator is described in this paper. The circuit works stably on the frequency 4.710 GHz (29th harmonic of loaded resonator) at about the -2 dBm level. In the construction, distributed-constant circuits have been applied. Commercially available SAW sensors usually work within the range of frequency from a few dozen to a few hundred megahertz. On the other hand, it is a well-known fact that the mass sensitivity of such devices is directly proportional to the square of its operating frequency, and SAW sensors for organic vapors, for instance, are usually mass sensitive. For this reason, an increase in the SAW sensors´ operating frequency seems to be useful. The circuit described in this paper shows the possibility of a dramatic rise in SAW operating frequency by exerting its operation through a specific high overtone (harmonic frequency) of the SAW resonator. The overtone frequency in such a solution then plays the role of basic mode. The oscillator proposed in this paper seems to be a good tool for chemisensitive-SAW-coating investigation
Keywords :
gas sensors; microwave oscillators; surface acoustic wave resonators; surface acoustic wave sensors; 4.710 GHz; SAW gas detectors; SAW resonator; SAW sensors; chemisensitive SAW coating; distributed-constant circuits; harmonic frequency; microwave resonators; operating frequency; organic vapors; overtone frequency; overtone oscillator; surface-acoustic-wave resonator; Chemical sensors; Chemical technology; Circuits; Frequency; Gas detectors; Oscillators; Substrates; Surface acoustic wave devices; Surface acoustic waves; Surface contamination; Microwave surface-acoustic-wave (SAW) stabilized oscillators; SAW sensors;
