A GSM LNA using mutual-coupled degeneration

This letter presents a low noise amplifier (LNA) input impedance matching technique using mutual coupled inductors. This scheme not only provides the required input impedance matching but also interstage impedance transformation for the cascoded transistor. The mutual coupled inductors also help to improve the circuit's reverse isolation. A 900-MHz global system for mobile communication LNA using this technique is designed and fabricated using 0.35-μm standard complementary metal oxide semiconductor technology. It achieves a 17-dB gain, 3.4-dB noise figure, and -5.1-dBm IIP3. The LNA draws 5.6 mA from a single 2.3-V power supply.