In this paper, a 5.8-GHz active mixer with the lowpower and the high conversion gain is designed and fabricated in the TSMC 0.18-m CMOS 1P6M process. The gate-driven circuit topology and the weak-inversion biasing techniques are employed to implement this mixer, and then achieve the power consumption of 1.13 mW (core circuit), the conversion gain of 8.62 dB, the LO driving power of -3 dBm, and the LO-RF isolation of 40 dB at 5.8 GHz. Based on the above-mentioned benefits, this mixer is suitable to be applied in the radiofrequency system-on-chip (RF SOC) development.