To improve IRRs of the system, two modules, RF filter and polyphase filter before the second downconersion, are added to the single-double quadrature structure.

• 为提高系统的镜像抑制性能，射频前端在单双正交结构的基础上添加两个模块：射频滤波器与第二次混频之前的多相滤波器。