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In this paper, the design and analysis of CMOS low-noise amplifiers (LNAs) with a magnetic coupled technique in different cascode topologies are proposed. To minimize the noise figure (NF) and the supply voltage, and to guarantee large 3-dB bandwidth, transformers are designed and placed between the transistors of the cascode devices. Three low supply voltage and wideband LNAs are designed, fabricated, and tested for demonstration. The first LNA uses the magnetic coupled cascode configuration. The second LNA is consisted of magnetic coupled cascode configuration with two amplification stages. The third one-stage LNA is based on the magnetic coupled triple cascode configuration. The first LNA is designed at Q -band while the others are designed at V-band, using 90-nm low-power CMOS technology. The Q-band LNA has a gain of 13.8 dB and an NF of 3.8 dB at 37 GHz, with a power consumption of 18 mW at 1.2-V supply voltage. The V-band cascode LNA has a gain of 17 dB at 57 GHz and an NF of 4.4 dB at 59.5 GHz with a power consumption of 19.2 mW at 1.2-V supply voltage. The V -band triple-cascode LNA has a gain of 13.7 dB at 54 GHz and an NF of 5.3 dB at 59.5 GHz, with a power consumption of 14.4 mW at 1.2-V supply voltage. Compared with the conventional cascode LNAs, the proposed magnetic coupled cascode LNAs have better NF, larger gain bandwidth product, and lower power consumption. The use of the magnetic coupled technique in a multicascode LNA significantly improves the gain performance with a slight degradation of the NF.
Microwave Theory and Techniques, IEEE Transactions on (Volume:60 , Issue: 12 )
Date of Publication: Dec. 2012