A transformer feedback low-noise amplifier (LNA) is implemented in a standard 180nm CMOS process, which exploits drain-to-gate transformer feedback technique for wideband input matching and operates across entire 2.5 ∼ 6.8 GHz ultra-wideband (UWB). The proposed LNA achieves a power gain of 11.5dB, an input return loss of greater than 15.0dB, and a minimum noise figure (NF) of 4.2dB, while consuming 8.1mW from a 1.8-V supply. To the best of the authors' knowledge, drain-to-gate transformer feedback for wideband input matching cascode LNA is the first adopted technique for UWB application.