Bipolar LNA design at different operating frequencies

The bipolar LNA design has been investigated at different operating frequencies. An innovative input matching network, which keeps the noise figure to a minimum, is presented and tested in a 900-MHz LNA. Compared to the state-of-the-art solution, the proposed approach does not impose any constraints on the bias current and/or the emitter area. Indeed, the current can be set to meet gain, linearity or power consumption requirements. In addition, the noise and the input impedance self-matching trend of a bipolar cascode topology at higher operating frequencies has been analytically studied and demonstrated by means of a 12-GHz LNA. The 900-MHz LNA exhibits a power gain of 16 dB and a noise figure of 0.8 dB by adding only one external inductor. The 12-GHz fully integrated input and output matched LNA shows a power gain of 9 dB and a noise figure of 4.7 dB. Bias currents are 2 mA and 4 mA, respectively, for the 900-MHz and the 12-GHz LNAs.