A low-power tunable SiGe HBT LNA for wireless LAN applications

This paper presents the design, implementation and measurements of a BiCMOS integrated tunable low noise amplifier for 5 GHz WLAN applications. It consists of a cascode gain cell, noise and power matched to a 50 Ω input source, and power matched to a 50 Ω load. In order to broaden the available bandwidth, the output matching network is modified by means of a shunt varactor, thus allowing the tuning of output matching and peak gain over a band exceeding 1 GHz. The proposed topology modification proofs to have neglectable effects on other LNA features, such as noise figure, linearity and input matching. Realized in a 120 GHz-f_t commercial BiCMOS technology, the circuit exhibits 13.2 dB of flat power gain, 2.3 dB of NF, -9 dBm of iIP₃, -20.5 dBm of P_{1 dBm} input and output return losses better than -10 dB in the 5-6 GHz band. Power consumption is 6 mW.