Balanced RF Duplexer with Low Interference Using Hybrid BAW Resonators for LTE Application

다국어 초록 (Multilingual Abstract)

A balanced RF duplexer with low interference in anextremely narrow bandgap is proposed. The Long-TermEvolution band-7 duplexer should be designed to prevent theco-existence problem with the WiFi band, whose fractionalbandgap corresponds to only 0.7%. By implementing a hybridbulk acoustic wave (BAW) structure, the temperaturecoefficient of frequency (TCF) value of the duplexer issuccessfully reduced and the suppressed interference for thenarrow bandgap is performed. To achieve an RF duplexer withbalanced Rx output topology, we also propose a novelbalanced BAW Rx topology and RF circuit block. The novelbalanced Rx filter is designed with both lattice- and ladder-typeconfigurations to ensure excellent attenuation. The RF circuitblock, which is located between the antenna and the Rx filter, isdeveloped to simultaneously function as a balance-tounbalancetransformer and a phase shift network. The size ofthe fabricated duplexer is as small as 2.0 mm × 1.6 mm. Themaximum insertion loss of the duplexer is as low as 2.4 dB inthe Tx band, and the minimum attenuation in the WiFi band isas high as 36.8 dB. The TCF value is considerably lowered to–16.9 ppm/ºC.

참고문헌 (Reference)

1 K.M. Lakin., "Thin Film Resonator Technology" 765-778, 2003

2 P-A. Girard., "High Performance Single-Balanced Duplexer" 861-864, 2007

3 K.M. Lakin., "Bulk Acoustic Wave Coupled Resonator Filters" 8-14, 2002

4 S.R. Gilbert., "An Ultra-Miniature, Low Cost Single Ended to Differential Filter for ISM Band Applications" 839-842, 2008

5 J.-S. Shin., "1-Chip Balanced FBAR Filter for Wireless Handsets" 1257-1260, 2010