In a multi-mixer system, a local oscillating signal used by a mixer may be coupled to others mixer, causing interference to the other mixers. In a multi-mixer system, there're more than one operating mixer and the local oscillating signal and its harmonics of one of the mixers can be an interference of other mixers. The interference can result in a de-sensitization of a receiver and results in unsatisfied signal quality in a communication system. Therefore, how to provide an interference reduction mechanism to lower the interference between mixers is an important topic.