Precision in-Situ Frequency Trimming Process of Surface Transverse Wave Resonators

Abstract

A method for frequency trimming of surface transverse wave (STW) resonators and oscillators in an in-situ monitoring process is presented. Compared to other known frequency trimming methods, such as heavy ion bombardment and reactive plasma etching, the suggested method is very simple and still allows sufficiently precise frequency adjustment. A practical frequency downshift of 1000 ppm does not affect the device insertion loss and, typically, increases the resonant loaded Q by 20 to 25%. Well controlled trimming rates in the 10 to 2000 ppm/minute are readily achievable. The method is easy to implement, does not affect the operation of the trimmed devices or oscillators during trimming, is harmless to the measurement equipment and can be automated to frequency trim several hundreds of STW devices or oscillators with one loading into the vacuum chamber.