A Novel Filter Construction Utilizing HTS Reaction-Type Filter to Improve Adjacent Channel Leakage Power Ratio of Mobile Communication Systems

We propose a new band selective stop filter construction to decrease the out of band intermodulation distortion (IMD) noise generated in the transmitting power amplifier. Suppression of IMD noise directly improves the adjacent channel leakage power ratio (ACLR). A high-temperature superconducting (HTS) device with extremely high-Q performance with very small hybrid IC pattern would make it possible to implement the proposed filter construction as a practical device. To confirm the effectiveness of the HTS reaction-type filter (HTS-RTF) in improving ACLR, investigations based on both experiments and numerical analyses are carried out. The structure of a 5-GHz split open-ring resonator is investigated ; its targets include high-unload Q-factor, low current densities, and low radiation. A designed 5-GHz HTS-RTF with 4 MHz suppression bandwidth and more than 40 dB MHz -1 sharp skirt is fabricated and experimentally investigated. The measured ACLR values are improved by a maximum of 12.8 dB and are constant up to the passband signal power of 40 dBm. In addition, to examine the power efficiency improvement offered by noise suppression of the HTS-RTF, numerical analyses based on measured results of gallium nitride HEMT power amplifier characteristics are conducted. The analyzed results shows the drain efficiency of the amplifier can be improved to 44.2% of the amplifier with the filter from the 15.7% of the without filter.

[1]  N. Roddis,et al.  HTS narrow band filters at UHF band for radio astronomy applications , 2005, IEEE Transactions on Applied Superconductivity.

[2]  Toshio Nojima,et al.  Microwave superconducting reaction-type transmitting filter using split open-ring resonator , 2006 .

[3]  Toshio Nojima,et al.  A 5 GHz high-temperature superconducting reaction-type transmitting filter based upon split open-ring resonators , 2008 .

[4]  Toshio Nojima,et al.  HTS split open-ring resonators with improved power-handling capability for reaction-type transmitting filters , 2007 .

[5]  Shoichi Narahashi,et al.  2-GHz Band Cryogenic Receiver Front End for Mobile Communication Base Station Systems , 2000 .

[6]  Kawaguchi Tamio,et al.  Development of Superconducting Filter for Meteorological Radar Systems , 2008 .

[7]  Zhi-Yuan Shen,et al.  Power handling capability improvement of high-temperature superconducting microwave circuits , 1997, IEEE Transactions on Applied Superconductivity.

[8]  J. Mazierska,et al.  Superconducting Technology: Development of a CDMA Base Station Cryogenic Front End Receiver , 2007, 2007 Asia-Pacific Microwave Conference.

[9]  E. M. Jones,et al.  Microwave Filters, Impedance-Matching Networks, and Coupling Structures , 1980 .

[10]  T. Nojima,et al.  Cuber predistortion linearizer for relay equipment in 800 MHz band land mobile telephone system , 1985, IEEE Transactions on Vehicular Technology.

[11]  Y. Ishikawa,et al.  Noise design of active feedback resonator BEF , 1993, 1993 IEEE MTT-S International Microwave Symposium Digest.

[12]  T. Nojima,et al.  Extremely low-distortion multi-carrier amplifier-self-adjusting feed-forward (SAFF) amplifier , 1991, ICC 91 International Conference on Communications Conference Record.