A 0.1–3 GHz, 90nm CMOS wideband LNA employing positive negative feedback for gain, NF and linearity improvement

A wideband LNA from 0.1-3 GHz, is designed in 90nm CMOS technology by applying positive-negative feedback to the conventional differential CG-LNA. The gain increases with simultaneous reduction in noise figure as a result of increase in overall effective transconductance due to application of both positive and negative feedback. Also, the positive-negative feedback improves linearity by cancellation of third harmonic. The design uses multi-fingered MOS transistors resulting in lowering of NF. The wideband input and output matching networks used provide better matching over the wideband. The LNA exhibits a voltage gain of 17 dB as its maximum value with flatness over the band, minimum noise figure of 2.73 dB. S11, S22<; -10 dB. The LNA shows an IIP3 of -0.867 dBm (at 1.575 GHz) while the core consumes 2.56 mA current from a 2 V supply.