A miniaturized monolithic low noise amplifier for 2.4/5.2/5.7 GHz WLAN applications using InGaP/GaAs HBT technology

This paper presents the design and experimental results of a 2.4/5.2/5.7 GHz triple-band low noise amplifier (LNA) achieved by switching between different base bias currents (I/sub B/) in use of InGaP/GaAs HBT technology for the first time. The first stage of the LNA provides high gain and input matching. The output matching of the second stage is realized by shunt-shunt feedback. It consumes only 7.7 mW power and achieves transducer gains (S/sub 21/) of 14.6 dB and 11/9.5 dB, input return losses (S/sub 11/) of -18.7 dB and -21.0/-11.5 dB, output return losses (S/sub 22/) of -20 dB and -22.7/-24.9 dB, reverse isolation (S/sub 12/) of -50.5 dB and -44.4/-44.4 dB, and noise figures of 3.35 dB and 2.54/2.71 dB at 2.4 GHz and 5.2/5.7 GHz, respectively. The LNA only occupies an area of 300 /spl mu/m /spl times/ 500 /spl mu/m excluding the test pads because only one inductor is used.