2 GHz surface transverse wave oscillators, design, performance and limitations

The current state-of-the-art for 2 GHz resonant devices and stable microwave oscillators using surface transverse waves (STW) is presented. Single mode low-Q resonators with an unmatched insertion loss of 4.85 dB, high-Q extended cavity resonators with an unloaded B of 3800 and an insertion loss of 10 dB, as well as 2-pole coupled resonator filters with a 3 dB bandwidth of 4 MHz and an insertion loss within 10 dB are described and characterized in detail. It is shown that the major loss mechanism in STW resonators, operating in the 2 GHz range, is the ohmic loss limiting the maximum achievable unloaded Q to about 75% of the material Q for SAW at this frequency. High-performance feedback oscillators are designed in a straight forward procedure using transistor and STW device S-parameters. Both stripline and lumped component designs provide elegant solutions to miniature 2 GHz oscillators with a temperature stability within 100 ppm over a (-20...+70) deg. C range and an output power in excess of +21 dBm.