• Title, Summary, Keyword: passband flatness

Search Result 13, Processing Time 0.043 seconds

A Varactor-Tuned RF Tunable Bandpass Filter with Improved Passband Flatness

  • Kim, Byung-Wook;Yun, Du-Il;Yun, Sang-Won
    • Journal of electromagnetic engineering and science
    • /
    • v.2 no.2
    • /
    • pp.124-127
    • /
    • 2002
  • A RF tunable bandpass filter using dielectric resonators and varactor diodes is redesigned to improve the passband flatness. Since the tunable liters are generally of narrow bandwidth and the Q value of the varactor diode is usually very low, the passband flatness is strongly deteriorated by sizeable distortion loss. To remedy this problem, we construct modified Chebyshev type filter by use of network synthesis techniques. The key of modified Chebyshev type filter is the rearrangement of the passband poles to improve the passband flatness. To maintain the constant passband bandwidth, design techniques of input/output stage and coupling windows are also applied. Experimental results show that the passband flatness can be improved by purposed method without any additional RF amplitude equalizer.

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
    • /
    • /
    • pp.13-16
    • /
    • 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.

  • PDF

A Design of BPF improved passband flatness (통과대역 평탄도를 개선한 대역 통과 여파기의 설계)

  • 황희용;김민지;김윤조;윤상원;장익수
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
    • /
    • /
    • pp.121-124
    • /
    • 2000
  • In mobile communication repeaters, very small size with sharp skirt response is needed as the BPF performances. The passband flatness of the proper BPF becomes very bad due to the low value of the resonator Q-factor used in the BPF. Which could girt serious level unbalance between channels. This flatness problem can he solved by a kind of compensated filler, which has 'reverse-curve'or 'concave shape'as the passband response. In this paper, the design method of the proposed 'concave bandpass filter'without matching and loss problems is presented. The designed and fabricated filter can properly and easily compensate the convex or bad flat passband response.

  • PDF

Design of Active Bandpass Filter Considering The Amplitude Flatness of Passband (대역 내 진폭 특성의 평탄도를 고려한 4단 능동 대역통과 여파기 설계)

  • Bang, Inn-Dae
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
    • /
    • /
    • pp.638-648
    • /
    • 2003
  • An active capacitance circuit is analyzed in depth and its application to active RF BPF with low noise figure is discussed. The characteristics of the active capacitance circuit made of FET[1] exhibits negative resistance and conventional capacitance, which is easily controlled. However, it is difficult to make the negative resistance adequate in the designated frequency range due to the lack of detailed analysis, which could make an active circuit unstable as the frequency is going higher or lower. In this paper, we analyzed the negative resistance characteristics of active capacitance circuits and also presented the method that the flatness of passband can be controlled. Finally we have designed a 4-stage active BPE, which results in bandwidth of 100 MHz, 0,04 dB insertion loss, 0.2 dB ripple, and noise figure of 2.4 dB at 1.75 GHz band.

  • PDF

Optimal design of linear-phase FIR digital filters with flat passbands and equiripple stopbands (평탄한 통과대역과 등리플 저지대역을 갖는 선형위항 FIR 디지탈 필터의 최적설계)

  • 정부영;이영국;김영권
    • 제어로봇시스템학회:학술대회논문집
    • /
    • /
    • pp.437-441
    • /
    • 1987
  • We have studied a new technical approach for the design of digital FIR filters with flatness in the passband, and equiripple attenuation in the stopband using the program of J.H. McClellan, T.W.Parks, L.R.Rabiner and the flatness property. The design technique directly loads to structures that have low passband sensitivity properties.

  • PDF

Design of 4-Pole Low Noise Active Bandpass Filter Improving Amplitude Flatness of Passband (통과대역 평탄도를 개선한 4단 저잡음 능동 대역통과 여파기 설계)

  • 방인대;전영훈;이재룡;윤상원
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.15 no.6
    • /
    • pp.590-598
    • /
    • 2004
  • An active capacitance circuit which employs series feedback network for the implement of negative resistance and low noise operation is analyzed in depth and its application to low noise active RF BPF's is discussed. Whereas many authors reported a lot of circuits that embody negative resistance circuit most of them have concerns for the equivalent resistance and reactance value at the center frequency. In this case, it could be possible to face a problem that the negative resistance circuit becomes unstable, or have poor flatness in passband because of insufficient forecast for the negative resistance values as the frequency goes higher or lower. In this paper, we extracted the exact equivalent values of this circuit and analyzed the RF characteristics with the varying the values of active devices and feedback circuits and presented the method that the flatness of passband can be improved. We have designed a 4-pole active BPF, which has the bandwidth of 60 ㎒, 0.67 ㏈ insertion loss, 0.3 ㏈ ripple, and noise figure of 3.0 ㏈ at 1.99 ㎓ band.

A study on 2-order BPF for improvement of passband flatness (통과대역 보상을 위한 2단 대역통과 여파기에 대한 연구)

  • Moon, Soo-Deok;Choi, Kyoung;Hwang, Hee-Yong
    • 한국정보통신설비학회:학술대회논문집
    • /
    • /
    • pp.137-140
    • /
    • 2005
  • 본 논문은 낮은 품질계수의 공진기를 사용한 여파기의 통과대역 평탄도를 개선하기 위한 2단 상보 여파기의 설계를 연구하였다. 품질계수로 인해 상보 여파기 평탄도 특성 변화를 고려하여 낮은 품질계수의 공진기를 사용하고, 기존의 여파기 설계공식에 그대로 적용할 수 있는 상보 여파기의 설계변수를 제시하였다. 제시한 설계변수로 상보 여파기를 설계하여 전체적인 통과 대역 평탄도를 1dB 이내로 만들 수 있었다.

  • PDF

An RF Amplitude Equalizer ; Improved Passband Flatness of a Bandpass Filter

  • Hwang, Hee-Yong;Jung, Jung-Seong;Yun, Sang-won
    • Journal of electromagnetic engineering and science
    • /
    • v.1 no.1
    • /
    • pp.83-87
    • /
    • 2001
  • Many communication systems require bandpass filters with sharp skirt frequency characteristics in order to avoid the interferencce, which results in more order in the filter design. However, because of the limited Q values bandpass filters made of small sized ceramic resonators suffer from relatively large ripples at the band edges as the order of the filter increases. In order to compensate the large ripples while maintaining the sharp skirt frequency we propose a new RF amplitude equalizer. The equalizer made of two pole bandpass filter and an amplifier whose amplitude characteristics are the reverse of those of the bandapss filter. At the cellular band 9-pole bandpass filter with 10 MHz bandwidth exhibits 3 dB ripple when 8mm*8mm ceramic coaxial resonators are used. We added the RF equalizer to this filter and the flatness is improved as less than 1 dB.

  • PDF

A design of V-shape RE Equalizer using dielectric resonator (유전체 공진기를 이용한 대역 평탄도 개선용 V-shape RF Equalizer의 설계)

  • 신재완;정중성;황희용;김윤조;류재수;정승환;윤상원
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
    • /
    • /
    • pp.132-135
    • /
    • 2002
  • A RF amplitude equalizer is designed to improve in-band flatness of Rf filters and/or systems using two dielectric resonators and a 90$^{\circ}$ hybrid. The equalizer has good return loss characteristics and V shaped S$_{21}$ response in passband which is suitable to compensate the ripple degradation due to insufficient quality factors of used resonators or narrow band width of filters or systems. After being connected to the equalizer, a 5-pole BPF at 1957MHz, which has 10 MHz bandwidth and 6㏈ ripple, shows only 1.8㏈ in-band ripple and good in- and out- band matched responses within used hybrid bandwidth without additional matching networks.

  • PDF

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
    • /
    • v.40 no.12
    • /
    • pp.155-160
    • /
    • 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.