MOSFET-only wideband LNA with noise cancelling and gain optimization

In this paper we present a MOSFET-only implementation of a balun LNA. This LNA is based on the combination of a common-gate and a common-source stage with cancelling of the noise of the common-gate stage. In this circuit, we replace resistors by transistors, to reduce area and cost, and minimize the effect of process and supply variations and mismatches. In addition we obtain a higher gain for the same voltage drop. Thus, the LNA gain is optimized and the noise figure (NF) is reduced. We derive equations for the gain, input matching and NF. We compare the performance of this new topology with that of a conventional LNA with resistors. Simulation results with a 130 nm CMOS technology show that we obtain a balun LNA with a peak 19.8 dB gain (about 2 dB improvement), a spot NF lower than 1.9 dB (0.5 dB reduction). The total power consumption is only 4.8 mW for a wide bandwidth higher than 6 GHz.