Frequency Tunable Bulk Acoustic Wave Resonators Based on the Acoustoelectric Effect

With the development of smart mobile communications, multiple bands are supported which leads to the requirement for tunable filters. Utilizing the acoustoelectric (AE) effect, a novel piezoelectric semiconductor tunable bulk acoustic wave (BAW) resonator is proposed. ScAlN and ZnO are selected as the piezoelectric and semiconductor layers. A precise multiphysics model is established to quantify the tuning performance of the AE effect in the BAW resonator. Under the guidance of the model, parameters are designed for a wide tuning range. Especially, the initial carrier concentration is optimized to avoid electrical disturbance of micro-acoustic mode excitation. The tuning range of the designed AE BAW resonator can achieve 5% and proper bias can compensate for the quality (Q) factor of anti-resonance. The resonator may be further integrated with variable capacitors in series to extend the tuning range of resonance and a reconfigurable filter with a 5% tuning range could be established. The resonator itself is also of great significance to voltage-controlled oscillators.