多传输零点LTCC带通滤波器的设计与实现

LTCC Bandpass Filter Design with Multi-Transmission Zeros

提出了一种阻带具有多个传输零点的带通滤波器设计方法,基于低温共烧陶瓷(LTCC)技术实现,可满足移动通信用滤波器小型化、高性能的要求。在电路设计中,通过改进滤波器谐振器结构,分别在阻带的低端近端、高端远端引入传输零点以提高带外抑制。借助三维仿真软件,进行指标、结构的仿真优化,设计并制作了一款尺寸为6 mm×3 mm×2 mm的LTCC滤波器,其中心频率f0=2.25 GHz,0.5 dB带宽不小于100 MHz,通带内损耗不大于1.8 dB,在1.33,1.78 GHz和二次谐波处均有传输零点。实测结果表明,该滤波器在阻带低端和二次谐波处有较好的抑制,因此其在移动通信系统中会有广泛应用。

A novel 3D low-temperature co-fired ceramic （LTCC） band-pass filter with multitransmission zeros is introduced to meet the miniaturization and high performance requirement of mobile communication system. By changing the structure of the filter resonator circuit, transmission zeros at low frequency and high frequency were introduced to enhance the stopband rejection. Then, a LTCC filter with size of 6 mm × 3 mm ×2 mm is designed with the heIp of 3D-simulation software. The center frequency of the filter is 2.25 GHz, and 0.5 dB bandwidth is no less than 100 MHz. The loss in the bandpass is no more than 1. 8 dB. This filer has transmission zeros locate at 1.33 GHz, 1.78 GHz and double frequecy respectively. Test results show that the filter has good selectivity at low frequency and good harmonic suppression. It could be well used in mobile communication system.