| Summary: | 碩士 === 國立交通大學 === 電機學院碩士在職專班電信組 === 98 === This thesis discussed a dual-band LNA realized in microstrip line circuits, and proposed a band pass filter with adjustable notches. LNA can simultaneously satisfy the demand of IEEE 802.11a (5.725-5.85GHz) and DBS (11.7-12.5GHz) receivers , in addition , the filter provides a lower insertion loss , but also resolves the problem of dual-band image signals in heterodyne down converters.
The dual-band LNA possesses 0.92dB and 1.21dB of noise figure within the two operation bands, 24dB conversion gain in average, and an improved input return loss no more than -10dB. The notched filter structures in SIR (Stepped Impedance Resonator), which can produce three adjustable notches by using asymmetrical inter-digital coupled lines. The frequency of the notches can be adjusted by varying the length of the open stubs on inter-digital fingers. The filter ideally provides an insertion loss lower than 1dB, a practical return loss higher than 15dB, and the image rejection reaches 32dB.
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