Summary
Resonant bridge oscillators for piezoelectric buzzers were
considered for 2-pin and 3-pin piezoelectric resonators in
series and parallel resonance modes. Note that only 2-pin
piezoelectric resonators operate at a precise resonant
frequency, so there is no 90-degree phase shift, which
varies with changes in frequency. The operational
frequency for the other oscillators is very close to the
resonant frequency and the reduction of the generated
power pressure is insignificant.