A new technique for the temperature compensation of SAW oscillators

A new method for the compensation of surface acoustic wave (SAW) oscillators is described. This work is a development of a technique first used for the compensation of oscillators employing AT-cut bulk wave resonators. The benefits that result for SAW oscillators are high compensation performance, low power consumption, low complexity and relatively small physical size. Compensation is achieved by the application of a control voltage to the oscillator, such that the oscillators frequency remains constant for variations in temperature. A custom bipolar integrated circuit has been designed which generates a power series representation of the control voltage. Prototype oscillators have been constructed at 600 MHz and show a compensated performance of +/- 3 p.p.m. over a 120 deg C operating temperature range (-40 to 80 deg C). The potential to improve the performance to better than +/-2 p.p.m. exists