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The simultaneous noise and impedance matching (SNIM) condition for a common-source amplifier is analyzed. Transistor noise parameters are derived based on the more complete hybrid-?? model, and the dominant factors jeopardizing SNIM are identified. Strategies for narrowband and broadband SNIM (BSNIM) are derived accordingly. A dual reactive feedback circuit along with an LC-ladder matching network is proposed to achieve the BSNIM. It includes a capacitive and an inductive feedback, where the former utilizes the transistor parasitic gate-to-drain capacitance and the latter is formed by transformer coupling. This circuit topology has been validated in 0.18- and 0.13- ??m CMOS technologies for a 3-11-GHz ultra-wideband (UWB) and a 2.4-5.4-GHz multistandard application, respectively. The 3-11-GHz UWB low-noise amplifier is detailed as a design example.