IF-Filters for Mobile Telephones
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| Title | IF-Filters for Mobile Telephones |
| Authors | |
| Abstract | Intermediate frequency (IF) filters for channel selection in mobile phone systems must offer narrow bandwidths together with very steep skirts and excellent stop band rejection. Surface acoustic wave (SAW) filters fulfil these requirements. But if conventional transversal design techniques are used chip sizes become too large. We therefore folded the propagation path of the SAW in order to make better use of the total chip length. Using two slightly inclined reflectors to a Z-shaped filter which conserves the temperature stability of the quartz substrate. At a center frequency of 45 MHz we developed filter on small chips with good pass band characteristics and an insertion filters better than 10 dB. A filter with signal suppression of 20 dB only 200 kHz from center frequency and an ultimate relative stop band rejection of 60 dB is shown. |
| Publisher | Faculty of Electrical Engineering and Computer Science |
| Date | 2011-07-07 |
| Source | Advances in Electrical and Electronic Engineering Vol 3, No 2 (2004): June |
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