An ultra-wideband (UWB) low-noise amplifier (LNA) implemented using 180 nm complementary metal-oxide- semiconductor technology is presented for wireless personal area network (WPAN) and wireless body area network (WBAN). Increasing the resistance of the substrate resistor RB reduces the noise factor. When additional substrate resistors and a composite feedback topology are employed, the proposed LNA can achieve both a 1.4 dB reduction of the noise figure (NF) and a 4 dB enhancement in power gain (PG). Over the operating frequency range from 3.1 to 4.8 GHz, the LNA achieves a maximum PG of 14.5 dB, a minimum NF of 1.5 dB, and an input return loss of < 10 dB. The measured current consumption is 3 mA with a 1.5 V supply voltage. The active chip area is 0.008 mm2. The proposed 3.1-4.8 GHz LNA has a superior NF, smaller active area, and the lowest dc power consumption compared with devices reported in the literature.