Design of a Dual-Band LNA with an adjustable image rejection Band-Pass Filter for DBS and 802.11a applications

• Main Authors: Chen, Po-Ian, 陳珀彥
• Other Authors: Jou, Christina-F.
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/56945597658735843898

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.