• Title, Summary, Keyword: Passband shaping

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Design of a Dielectric Resonator Filter with Improved Flatness Passband for WiBro band (통과대역 내 평탄도를 개선한 휴대인터넷 대역 유전체 공진기 여파기 설계)

  • Lee, Song-Yi;Yun, Sang-Won
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • pp.13-16
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    • 2005
  • Many mobile communication systems require bandpass filter with sharp skirt characteristics and consequently a filter was formed by more order. It needs to improve flatness in passband. In this paper, amplitude equalizer was used to improve the flatness of passband. We modified Chebyshev prototype filter by use of network synthesis and computed the prototype elements for Shaping filter. We designed and realized a 13-order combline bandpass filter and 4-order amplitude equalizer with coaxial dielectric resonators at WiBro band. The measured results show $\pm$0.82 dB amplitude difference in passband, 6 dB improved flatness.

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Sidelobe Suppression Enhancement of Radiofrequency Photonic Filters via Time-to-frequency Mapping

  • Song, Min-Hyup
    • Journal of the Optical Society of Korea
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    • v.18 no.5
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    • pp.449-452
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    • 2014
  • We present a multi-tap microwave photonic filter with high selectivity through applying time-to-frequency mapping and optical frequency comb shaping techniques. When arranged in the time-to-frequency mapping stage, by a Fourier transform, the deviation of the optical taps to the target profile is significantly reduced while maintaining the apodization profile, resulting in high sidelobe suppression in the filters. By applying a simple time-to-frequency mapping stage to the conventional optical frequency combs, we demonstrate a substantially enhanced (>10dB) sidelobe suppression, resulting in filter lineshapes exhibiting a significantly high (>40dB) main lobe to sidelobe suppression ratio. These results highlight the potential of the technique for implementation in various passband filters with high sidelobe suppression.

Photonic K-Band Microwave Bandpass Filter with Electrically Controllable Transfer Characteristics Based on a Polymeric Ring Resonator (전기적으로 가변되는 전달특성을 갖는 폴리머 링 광공진기를 이용한 마이크로웨이브 대역통과 필터)

  • Kim, Gun-Duk;Lee, Sang-Shin
    • Korean Journal of Optics and Photonics
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    • v.17 no.5
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    • pp.475-479
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    • 2006
  • An integrated photonic K-band microwave bandpass filter has been proposed and demonstrated by incorporating a polymeric ring resonator. Its transfer characteristics were adjusted by shilling the resonance wavelength of the ring resonator via the thermooptic effect. The achieved performance of the filter includes the center frequency of 20 GHz, the attenuation of ${\sim}15dB$, the bandwidth of 2 GHz, and the corresponding quality factor of 10. The microwave output power within the passband of the device was adjusted at the rate of about 6.7 dB/mW in the range of 27 dB. This kind of device with electrically controllable transfer characteristics can be applied to implement microwave switches and other devices.

Design of Cic roll-off Compensation Filter in Digital Receiver For W-CDMA NODE-B (W-CDMA 기지국용 디지털 수신기의 CIC 롤 오프 보상필터 설계)

  • 김성도;최승원
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.12
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    • pp.155-160
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    • 2003
  • Owing to the advances in ADC and DSP technologies, signals in If band, which once had to be processed in analog technology, can new be digitally processed. This is referred to as "Digital IF" or "Digital Radio", which is a preliminary stage of SDR. Applying the digital radio technology to a multi-carrier receiver design, a processing gain is generated through an over-sampling of input data. In the digital receiver, decimation is performed for reducing the computational complexity CIC and half band filter is used together with the decimation as an anti-alising filter. The CIC filter, however, should introduce the roll-off phenomenon in the passband, which causes the receiving performance to be considerably degraded due to the distorted Passband flatness of receiving filter. In this paper, we designed a CIC roll-off compensation filter for W-CDMA digital receiver. The performance of the proposed compensation filter is confirmed through computer simulations in such a way that the BER is minimized by compensating the roll-off characteristics.off characteristics.