Design Issues for Low Voltage Low Power CMOS Folded Cascode LNAs

Design and simulation results of fully integrated 5-GHz CMOS LNAs are presented in this paper. Three different input impedance matching techniques are considered. Using a simple L-C network, the parasitic input resistance of a MOSFET is converted to a 50 Ω resistance. As it is analytically proved, that is because the former methods enhance the gain of the LNA by a factor that is inversely proportional to MOSFET’s input resistance. The effect of each input impedance matching on the amplifier’s noise figure and gain is discussed. By employing the folded cascode configuration, these LNAs can operate at a reduced supply voltage and thus lower power consumption. To address the issue of nonlinearity in design of low voltage LNAs, a new linearization technique is employed. As a result, the IIP3 is improved extensively without sacrificing other parameters. These LNAs consume 1.3 mW power under a 0.6 V supply voltage.