This paper presents a novel low power high linear CMOS sub-harmonic mixer for direct-down conversion receivers, in which an inductive connection between RF and LO stages is used to improve the linearity and enhance the gain of Mixer. A comparison is done between two circuits for two possible conditions, High Gain Medium Linearity (HGML) and High Linearity Medium Gain (HLMG), and recently published works. Simulation results performed by Advanced Design System (ADS) in 0.18µm TSMC CMOS process show that the proposed mixer has exhibited better performance without increasing power consumption of 5mw. For HGML the inductive connection between RF and LO stages causes an enhancement of 6dB for conversion gain, 3.63dB for DSB NF and 4.7dBm for IIP3. For HLMG condition, it shows a conversion gain of 8.5dB, DSB noise figure of 13.58dB, input referred 1dB compression point of -14dBm and the IIP3 of 2.5dBm.