低频宽带陶瓷滤波器

介绍了一种中心频率为450 kHz,相对带宽大10％的低频压电陶瓷滤波器的设计.它具有低插损、高选择性及高稳定性的特点.该文通过利用两种机电耦合系数不同的压电陶瓷材料分别制备串臂陶瓷振子和并臂陶瓷振子,达到了小波动大带宽的设计结果,并找出了串、并臂陶瓷振子的最佳静电容比,解决了调试匹配难题；通过在陶瓷振子四周梅花成型方式的设计,抑制了谐波响应,提高了产品的带外寄生抑制；通过优化设计专用装连结构,在满足小尺寸外形要求下,保证了产品的可靠性.

Study on a Piezoelectric Ceramic Filter with Low Frequency and Wide Bandwidth

The design of a piezoelectric ceramic filter with the center frequency of 450 kHz and bandwidth of greater than 10% has been presented in this paper.It has the features of low insertion loss,high selectivity and excellent stability.Two piezoelectric ceramic materials with different electro-mechanical couple factor have been used for fabricating the series and parallel arms ceramic vibrators respectively to realize small fluctuation and wide bandwidth.The optimal static capacitance ratio between the series arm vibrator and the parallel arm vibrator has been obtained thus the difficulty in debugging for matching has been overcome.By using the quincunx layout around the ceramic vibrator,the harmonic response has been suppressed and the performance of the out-of-band spurious suppression has been improved.By optimizing the design of the special fixing structure the reliability of the filter can be ensured on satisfying the requirement of small size.