专利名称：Notch filter发明人：Wright, Peter V申请号：EP87302122.4申请日：19870312公开号：EP0255195A2公开日：19880203
专利附图：
摘要：A notch filter includes a quadrature coupler (26) having first, second, third, andfourth terminals (28,30,32,34), the first terminal being a signal input terminal and thefourth terminal being a signal output terminal. A first tuned surface acoustic wave (SAW)device (10), coupled to the second terminal, receives the input signal with 0° phase shift,
and a second tuned SAW device (10), coupled to the third terminal, receives the inputsignal with a 90° phase shift. Each SAW device has primarily reactive characteristics atsignal frequencies higher or lower than the notch region and primarily resistivecharacteristics across the notch region. Each tuned surface acoustic wave devicecomprises a SAW impedance element (12) having an input admittance which is
substantially constant in both magnitude and phase over a predetermined band widthacross the notch region and an inductor (14) tuning the SAW element. The quadraturecoupler preferably comprises four inductors (36,38,40,42) which are serially connected toform a continuous circuit. A respective one of first to fourth terminals is coupled to ajunction between a respective pair of the serially-connected inductors, and a respectivecapacitance (52) is coupled between each of the terminals and a ground potential.
申请人：R.F. MONOLITHICS, INC.
地址：4441 Sigma Road Dallas Texas 75244 US
国籍：US
代理机构：Brunner, Michael John
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