A single-ended amplifier with a magnetic-coupled feedback embedded network is proposed and its small-signal equivalent circuit is analysed in detail. The embedded network cancels the effects of the gate-drain capacitor Cgd and introduces negative resistance into the transistor drain, so that the maximum power gain of the transistor could be achieved. Based on this design methodology, a 142 GHz amplifier with 18.5 dB power gain and 7.9 mW DC power has been implemented in 65 nm CMOS.