Design of an input matching network for RF CMOS LNAs using stack inductors

This paper presents a low noise amplifier (LNA) with an input impedance matching technique using mutual coupled stack inductors. Two different input matching methodologies using mutual inductors are evaluated in terms of their effect on the gain and NF of RF CMOS LNAs in 2.4 GHz. Design guidelines to improve the gain-NF performance of CMOS LNAs are developed by means of analytical expressions. Moreover, it is demonstrated that the NF of the LNA can be minimized in negative mutual coefficient methods by properly choosing the size of the active and passive components. A 2.5-GHz global system for Bluetooth communication LNA using this technique is designed and simulated using 0.35-um standard 2P4M complementary metal oxide semiconductor technology. It achieves an 18-dB gain, 2.47-dB noise figure, and -5.2-dBm input referred IIP3 with -100m for coupling coefficient. The LNA draws 6.4 mA from a single 3.3-V power supply.