On some properties of the output of a pulsed digital oscillator working with multiple resonances

In this paper, we study the possible output of the pulsed digital oscillator (PDO) with multiple resonant modes of the mechanical resonator in the feedback loop. PDOs are simple circuits that allow linear resonators to maintain self-sustained oscillations and can work as mass-change resonant sensors. For
a resonant sensor, activation of higher vibration modes of a mechanical resonator can be a way to improve its performance.
We show that the location of the sensing/actuation system affects the output and can enhance higher mechanical modes.