The performance of local oscillator anti-phase balance mixer is analyzed by using the system analysis method. Then, a double balance mixer is designed by adopting the LT5522 chip. Finally, the practicality circuits of a receiver are tested and analyzed. A mirror frequency suppression filter is configured at the input end of the mixer, and a low noise amplifier is configured at the input port. By doing so, the whole down-mixer circuits observe a better noise factor, and this noise factor is less than 1.2 dB of the whole circuits to satisfy the needs.