A dedicated RF module for 85Rb atomic clock chip is designed in order to implement a low power and miniature atomic clocks. The structure of 85Rb atomic clock chip dedicated RF modules is described. The chip employs a cross-coupled differential structure, and utilizes planar integrated spiral inductor in series to ensure the output frequency can reach 3 GHz. The chip uses the accumulation mode MOS varactors, and realizes the monotone adjustment on the output frequency by controlling the voltage. The simulation test is performed on the chip, then the flow sheet and packing are completed. The results basically reach the design specifications.