Surface transverse wave oscillators with extremely low thermal noise floors

This paper presents state-of-the-art results on 1 GHz surface transverse wave (STW) power oscillators running at extremely high loop power levels. High-Q single-mode STW resonators used in these designs have an insertion loss of 3.6 dB, an unloaded Q of 8000, a residual phase noise of -142 dBc/Hz at 1 Hz intercept and operate at an incident power of up to 31 dBm in the loop. Other low-Q STW resonators and coupled resonator filters (CRF) with an insertion loss in the 5-9 dB range can conveniently handle power levels in excess of 2 W. These devices were implemented in voltage controlled oscillators (VCO´s) running from a 9.6 V source at an output power of 23 dBm and a RF/dc efficiency of 28%. Their tuning range was 750 kHz and the noise floor -180 dBc/Hz. The oscillators, stabilized with the high-Q devices, use specially designed AB-class power amplifiers, deliver an output power of 29 dBm and demonstrate a noise floor of -184 dBc/Hz and a 1 Hz intercept of -17 dBc/Hz. The 1 Hz intercept was improved to -33 dBc/Hz using the UTO-1023 as a loop amplifier. In this case the output power was 22 dBm. In all cases the loop amplifier was the limiting factor for the close-to-carrier oscillator phase noise performance