公开(公告)号：US06541893B2

公开(公告)日：2003-04-01

申请号：US09873499

申请日：2001-06-04

申请人： Jiahua Zhu ,  Yicheng Lu ,  John Kosinski ,  Robert Pastore

发明人： Jiahua Zhu ,  Yicheng Lu ,  John Kosinski ,  Robert Pastore

IPC分类号： H03H925

CPC分类号： H03H9/6403

摘要： A novel programmable SAW filter with switchable multi-element interdigital transducers (IDTs) controlled by a microprocessor or a computer is provided that realizes the tunability of both center frequency and bandwidth of the SAW filter. The filter possesses the feature of the programmability of both center frequency and 3 dB bandwidth. As an example design, the center frequency of the SAW filter ranges from 126.8 MHz to 199.1 MHz while the 3 dB bandwidth ranges from 18.8 MHz to 58.9 MHz. The multi-input configuration increases the programmability of the device and improves insertion loss. A matching network for the programmable SAW filter further improves insertion loss level and stopband attenuation. A resistance weighting method has been applied to improve in band ripple with the passband ripple being reduced from 6.44 dB to 1.37 dB after resistance weighting. The prototype of programmable SAW filter simplifies the device structure and fabrication process by eliminating the tap weighting and summing circuits, resulting in a smaller device and lower costs. Moreover, frequency response shaping is realized without apodization.