In this paper, we report a piezoelectric phononic crystal plate featuring broadband wave attenuation. In the piezoelectric phononic crystal system, the transmitted elastic wave is attenuated owing to destructive interference by taking advantages of phase difference. The proposed concept is applied to a piezoelectric phononic crystal plate synthesized by functional dual-lane units that yields phase difference. Whereas, the piezoelectric unit-cells are connected negative capacitance shunt circuits individually. Our analysis shows that the coupled phononic crystal has a strong broadband low-frequency wave attenuation capability. The bandwidth of 10 dB wave attenuation is broadened by 34 times in the vicinity of 5 kHz comparing to that of a local resonance metamaterial under the same mechanical configuration. Moreover, the frequency range of wave attenuation of the proposed system can be online adjusted through the modification of the external shunt circuits.