This paper presents a millimeter-wave (mmW) frequency doubler based on complementary push-push (CPP) configuration achieving wideband, low-power and high-efficiency operation. Conventional push-push (PP) frequency doublers typically rely on half-wave rectification and suffer from performance compromise between the desired output and the DC current consumed. To mitigate this issue, a simple but effective CPP frequency doubling scheme is proposed to realize full-wave rectification, attaining enhanced output harmonic current and improved fundamental rejection without extra power consumption. At the output, an implicit dual-resonance (IDR) network featuring inherent resonant frequency alignment is employed to efficiently combine the harmonic power generated by the CPP transistors. Implemented in a 65-nm CMOS process and occupying a core area of 0.04 mm2, the proposed frequency doubler prototype measures conversion loss of < 10 dB from 53 to 78.5 GHz at 0-dBm input, while consuming 21.5 mW from a 1-V supply.