A 3–5 GHz ultra wideband common-gate low noise amplifier

In this paper, designing an ultra wideband 3-5 GHz CG LNA in two different styles with active and passive output matching using 0.18 μm CMOS process is presented. A wider bandwidth and reduced linearity is observed in active output whereas in passive mode a better performance of linearity but reduced bandwidth is achieved. As the circuitry in active mode to increase linearity and having a more excess transistor, dissipation is more in comparison with passive one. Using a shunt-series broadening technique at the output of the main stage has a roll of optimization of gain and controlling the bandwidth. By using a 1.8 v power supply a power gain of more than 10.5 dB, input reverse isolation less than -10.3 dB noise figure of about 4 dB and IIP3 in center frequency of 4 GHz about -4.4 dBm which dissipates less than 12 mw in active mode in 3-5.5 GHz frequency band is observed. In passive output mode with reduced dissipation, using 1.2 v power supply a power gain of more than 10 dB, input reverse isolation less than -10 dB, noise figure of about 4 dB and IIP3 in center frequency of 4 GHz about -2.5 dBm with dissipation of less than 6mw in 3-5 GHz frequency band is attained.