# Micro-Acoustic Sources

One of the activities of CoSyMA team is dedicated to embedded sources based on piezoelectric component

A source design criterion is the improvement of phase noise and short-term stability (Allan variance). For an embedded source, size and consumption must also be taken into account. Leeson's theory shows that the improvement of the phase noise requires the improvement of the quality factor (Q) of the resonator. An improvement of the quality factor by a factor of ten leads to a decrease in the noise in f -3 of -30 dBc. J.J. Gagnepain et al. shows that for a BAW, the frequency noise in 1 / f is inversely proportional to Q4? [1] . In addition, a multiplication of the frequency f of the oscillator by ten leads to a degradation of the whole of the phase noise curve by +20 dBc. The frequency of Leeson is given by the ratio of the working frequency of the oscillator to twice the quality factor of the resonator. Thus, in the various systems using an embedded source, RADAR or interrogation electronics, the phase noise of the oscillator beyond 1 or 10 kHz of the carrier can quickly limit the performance of the system. Increasing the resonant frequency and quality factor of the resonators is paramount. The figure of merit taken into account for resonators dedicated to the sources is the Q × f product. Figure illustrates a result obtained.