Low Phase Noise RF Oscillators Based on Thin-Film Lithium Niobate Acoustic Delay Lines.

An RF oscillator has been demonstrated using a wideband SH0 mode lithium niobate acoustic delay line (ADL). The design space of the ADL-based oscillators is theoretically investigated using the classical linear time-invariant (LTI) phase noise model. The analysis reveals that the key to low phase noise is low insertion loss (IL), large delay (τG), and high carrier frequency (ƒo). Two SH0 ADL oscillators based on a single SH0 ADL (fo = 157 MHz, IL = 3.2 dB, ƒG = 270 ns) but with different loop amplifiers have been measured, showing low phase noise of −114 dBc/Hz and −127 dBc/Hz at 10-kHz offset with a carrier power level of −8 dBm and 0.5 dBm, respectively. These oscillators not only have surpassed other Lamb wave delay oscillators but also compete favorably with surface acoustic wave (SAW) delay line oscillators in performance. [2019-0223] [ABSTRACT FROM AUTHOR]