Low noise, microwave signal generation using bulk and surface acoustic wave resonators

The use of high-Q bulk and surface acoustic wave resonators, which provides a means for generation of low-noise microwave carrier signals, is discussed. The resulting signal phase noise spectrum consists of two distinct regions. In the near-carrier region, the spectrum is characterized by flicker of frequency noise usually due to short-term instability in the oscillator acoustic resonator itself. The spectral density of the fractional frequency fluctuations provides a convenient measure for comparing the short-term frequency stability of resonators operating in different frequency ranges. The lowest near-carrier noise levels are obtained by frequency multiplication of a lower frequency oscillator using a correspondingly higher Q resonator. Frequency multiplication, however, results in higher relative noise floor levels at high carrier offset frequencies. Techniques for obtaining low-noise floor levels are discussed. In addition, HBAR (high overtone, bulk acoustic resonator) and UHF HBAR oscillator performance are described