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3. TECHNICAL BRIEF
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3.5.7. UMTS Rx RF Filter
Filter1 : 869 ~ 894 MHz
Filter2 : 1805 ~ 1880 MHz
An RF filter is located between the UMTS LNA and mixer. Insertion loss is important, but not as critical
as losses before the LNA. The most important parameters of this component include:
■ Out-of-band rejection or attenuation levels, usually specified to meet these conditions:
- Far out-of-band signals - ranging from DC up to the first band of particular concern and from the
last band of particular concern to beyond three times the highest passband frequency.
- Tx-band leakage - the transmitter channel power, although attenuated by the duplexer, still
presents a cross-modulation threat in combination with Rx-band jammers. The RF filter must
provide rejection of this Tx-band leakage.
- Other frequencies of particular concern . bands known to include other wireless transmitters that
may deliver significant power levels to the receiver input.
Figure. 3.5.7 WCDMA Rx SAW Filter Specification
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