Extremely low thermal noise floor, high power oscillators using surface transverse wave devices

Abstract

Abstruct-This paper presents state-of-the-art results on 1-GHz surface transverse wave (STW) oscillators running at extremely high loop power levels. The 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 PM noise of -142 dB&z at a 1-Hz carrier offset, 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 insertion losses in the 5-9 dB range, can conveniently handle power levels in excess of two Watts. These devices were incorporated into voltage controlled oscillators (VCO's) running from a 9.6-V dc source and provide an RF output power of +23 dBm at an RF/dc efficiency of 28%. Their tuning range was 750 kHz and the PM noise floor was -180 dBc/Hz. The oscillators, stabilized with the high-& devices and using specially designed AB-class power amplifiers, delivered an output power of +29 dBm and exhibited a PM noise floor of -184 dBc/Hz and a 1-Hz phase noise level of -17 dBc/Hz. The 1-Hz phase noise level was improved to -33 dBc/Hz using a commercially available loop amplifier. In this case, the output power was +22 dBm. In all cases studied, the loop amplifier was found to be the factor limiting the close-to-carrier oscillator phase noise performance.

Phase noise performance of low voltage surface transverse wave oscillators in the 0.9 to 2.4 GHz range

“…The degradation w. r. t. the 2.5V tuning voltage is with 7 dB not so dramatic which is attributed to about 2 dB of gain compression at that edge frequency. The data in Table I is consistent with the results reported in [8] and again verify the importance of keeping the gain compression as low as possible for minimum phase noise. The phase noise plots in Fig.…”

“…As shown in the table, except for the high output power and RF/DC efficiency, these oscillators feature an excellent stability w. r. t. supply voltage variations. Phase noise levels are close to those achieved with state-of-the-art STW oscillators operating at much higher supply voltages (15V) and using very expensive screened amplifiers [8].…”

“…10 and 9 c). Keeping in mind that in a STW oscillator, the ssustaining transistor is always the dominant source of 1/f noise [8], the lower Q of that STW resonator results also in a higher close-in phase noise [1] of the 915 MHz oscillator, compared to the 1.25V 1 GHz LVVCSO. On the other hand, the noise floor of this 915 MHz oscillator goes down to -174 dBc/Hz which, on one hand, is a attributed to the higher 11 dBm of output power and loop power accordingly, on the other hand, since no tuning was required for The experimental verification of the boost converter principle at microwave frequencies is extremely difficult, since one needs high impedance oscilloscopes with a bandwidth at least 10 times higher than the fundamental oscillator frequency to visualize the expected narrow pulses at the collector of the switching transistor Q1 from Fig.…”

“…• Due to the high loop power [8], very low thermal noise floor levels are possible at supply voltages ranging from 1.2 to 5V [4,6].…”

Thin film plate acoustic resonators for integrated microwave power oscillator applications

“…(1) With f 0 ¼ 880 MHz, Q L ¼ 720 and the flicker noise constant of the sustaining amplifier measured as a E ¼ 2.2 × 10 214 Hz [5], for the FPAR flicker constant we calculate a R ¼ 2.1 × 10 236 /Hz. This value is comparable with some of the best SAW resonators built to date [5].…”