A dual-peak maximum achievable gain core design technique is proposed. It has been adopted into a 4-stage wideband amplifier. Implemented in a 65nm CMOS, the amplifier achieves 3dB bandwidth of 30GHz (230 similar to 260GHz), gain of 12.4 +/- 1.5dB, and peak PAE of 1.6% while dissipating 23.8mW, which corresponds to the widest bandwidth and highest gain per stage among other reported CMOS amplifiers operating above 200GHz.