Title :
Correspondence - Design of ladder-type SAW/BAW
Author :
Hualei Wang ; Jing Chen ; Yu Shi ; Omori, Tatsuya ; Changjun Ahn ; Hashimoto, Koji
Author_Institution :
State Key Lab. of Electron. Thin Films & Integrated Devices, Univ. of Electron. Sci. & Technol. of China, Chengdu, China
Abstract :
This paper describes the design of RF SAW/ BAW filters with constant group delay. The band-pass LC filter is designed based on the traditional Bessel filter design. Then, LC resonators in the filter are replaced by SAW/BAW resonators with finite capacitance ratio γ. Finite γ generates passband ripples in the group delay. However, it is shown the ripples can be suppressed by optimal design of the SAW/BAW resonators. Norton´s first transform is also applied to the designed filter to reduce variation of resonator shunt capacitances. Finally, extremely flat group delay with deviation of 4 ns over the frequency range of ±20 MHz at the center frequency of 1 GHz is theoretically demonstrated.
Keywords :
band-pass filters; bulk acoustic wave devices; radiofrequency filters; surface acoustic wave filters; Bessel filter design; LC resonators; Norton first transform; band-pass LC filter; constant group delay; finite capacitance ratio γ; frequency -20 MHz to 20 MHz; frequency 1 GHz; group delay; ladder-type RF SAW-BAW filter design; optimal design; resonator shunt capacitances; Band pass filters; Capacitance; Delay; Low pass filters; Passband; Resonant frequency; Resonator filters;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2012.2523
