What’s the piezoelectric ceramic oscillator

 A piezoelectric ceramic is a resonant body, and when it is used as a piezoelectric element, it is called a piezoelectric vibrator or a piezoelectric ceramic vibrator. With the resonance characteristics, many devices can be fabricated, such as filters, piezoelectric ceramic transformers, and so on.Performance parameters of piezoelectric ceramic oscillator including electromechanical coupling coefficient are parameters reflecting the conversion relationship between piezoelectric ceramic mechanical energy and electrical energy. It is defined as the ratio of the electromechanical interaction energy density (also called piezoelectric energy density) to the geometric mean of the elastic energy density and the dielectric energy density. The electromechanical coupling coefficient is not only related to the performance of the piezoelectric material, but also related to the geometry and vibration mode of the piezoelectric vibrator. Therefore, the electromechanical coupling coefficients are corresponding to the vibrators of different shapes and vibration modes are different. 

The mechanical quality factor is the mechanical loss of the PZT5 material piezo ceramics oscillator. It is one of the important parameters to measure the performance of the piezoelectric ceramic material. The frequency constant N is the product of the resonant frequency of the piezoelectric ceramic oscillator and the dimension along the vibration direction is constant. This constant is called the frequency constant. The frequency constant is only related to the nature of the material and the mode of vibration. The electrostatic capacitor C0 static capacitance mainly reflects the dielectric constant of the piezoelectric material. The size of the static capacitance C0 is not only related to the performance of the piezoelectric ceramic material, but also related to the geometry of the vibrator. In the filter design, it directly affects the filter impedance level.

Relative bandwidth

       The relative bandwidth of the piezo ceramic material vibrator is the difference between the parallel resonant frequency and the series resonant frequency divided by the series resonant frequency.

Its size is related to the formulation of the material, the manufacturing process and the vibration mode. The dielectric loss and the electrical quality factor are the dielectric losses caused by the heating of thePZT piezoelectric ceramic under an alternating electric field. The dielectric loss consists of polarization loss and dielectric loss. The dielectric loss is generally expressed by the loss angle. There are two equivalent circuits and calculation methods: serial equivalent circuit and parallel equivalent circuit.  

 (1) Serial equivalent circuit 

Cp and R are the static capacitance and loss resistance of the parallel equivalent circuit, respectively. The reciprocal of the dielectric loss tangent 1/tan δ is called the electrical quality factor Qe of stock piezo ceramic.