dualband_study_lna - Study and Design of the Dual-Band Low...

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Study and Design of the Dual-Band Low Noise Amplifier Wu Pan, Bing Long, Jianhui Ye Institute of MOEMS, Chongqing University of Posts and Telecommunications Chongqing 400065, P. R. China Abstract - A dual-band source-inductive-degeneration cascoded low noise amplifier, whose center frequencies are 940MHz and 2020 MHz respectively, based on common usage of the component independent of the frequency, was investigated and designed in this paper. The interstage mutual coupled inductors provide the required input impedance matching and interstage impedance transformation. The circuit’s reverse isolation for the cascoded LNA is improved. The parallel capacitance between the MOSFET’s gate and source optimize noise factor of the LNA. The matching network design, the noise optimizing were analyzed hereof. The development of LNA and the methods of NF optimization were studied. The designed LNA achieves power gains of 26dB and 25dB, and minimum noise figure of 1.1 dB and 2.0 dB, and power of 10.5mw with 1.5 voltages respectively. I. INTRODUCTION CMOS technology gradually becomes a technology suited to fabricate low cost, high-integration density mobile terminal along with the reduction of gate length of CMOS component [1-5] . At present, it is certain trend that multi-standard RF COMS monolithic receiver is used in the mobile communication systems, and the low noise amplifier (LNA) is a bottleneck of receiver design in the multi-standard monolithic integrated mobile communication systems. In the paper, the dual-band LNA is designed based on the same MOSFET, the optimization design of its input network and it has dual-band selective function. Consequently, the cost of receiver is reduced, the integration level is increased and the number of transistors is reduced. A dual-band LNA operated on 2020MHz and 940MHz is designed by using BSIM3 models, its matching network and noise analysis are researched. These researches are useful to the design of CMOS wireless communication receiver. II. DESIGN OF MATCHING NETWORK It is noteworthy that the performance of wireless receiver system is affected by input matching of LNA, which should be made account of in the design. At present, the topology which be adopted widely in the LNA is source electrode negative feedback because it can obtain low noise figure and better gain, shown in Fig.1. Its input impedance is expressed by 1 1 () m in g s s gs g Z jL L L jC C ω =+ ++ . (1) In order to obtain the impedance matching of 50 Ω , at the resonance frequency, 0g s 1/ ( ) L LC , the imaginary part of (1) is zero, the real part of (1) is 50 Ω . This topology belongs to single band input matching. In the design of dual-band LNA, this topology should be modified and optimized. Shown as figure 2, the back isolation characteristic of the circuit is increased by using interelectrode inductance, and the interelectrode impedance transformation and input impedance matching are provided.
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This note was uploaded on 09/19/2010 for the course EE 7V88 taught by Professor Dr.karba during the Fall '09 term at University of Texas at Dallas, Richardson.

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dualband_study_lna - Study and Design of the Dual-Band Low...

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