一种无源高线性混频组件的设计与实现

在射频通信系统中,混频器作为接收机的核心器件,其线性指标将直接影响整个接收系统的性能。文中设计并实现了一种无源高线性混频组件电路,采用“平衡混频器+吸收式滤波器”的方式达到了高线性要求。平衡混频器采用一对双平衡混频器互联,通过相位抵消达到优化线性的目的;吸收式滤波器吸收混频器产生非线性谐波,使其无法在空间中进行反射,两者共同作用优化了组件整体的线性指标。测试显示,在射频频率为30~1 350 MHz,本振频率为3 030~4 350 MHz,中频频率为3 000 MHz的条件下,混频组件的IIP₂可以达到94 dBm,IIP₃可以达到29 dBm。相比于单独混频器,新电路的线性性能得到极大的优化,更适合高性能的接收机使用。

Design and Implementation of a Passive High Linear Mixing Component

In the RF communication system, the mixer acts as the core device of the receiver, and its linearity directly affects the performance of the entire receiving system. A passive high linear mixing component circuit with the method of the “balanced mixer + absorption filter” to achieve high linearity requirements was designed and implemented in this paper. The balanced mixer was interconnected by a pair of double balanced mixers and the linearity was optimized with the phase cancellation. The nonlinear harmonics generated by the mixers were absorbed by the filter, which blocked the reflection in the space. The two parts worked together to optimize the linearity of the entire component. After actual testing, the IIP₂ of the mixing component could reach 94 dBm and the IIP₃ could reach 29 dBm with the RF frequency of 30~1 350 MHz, the local oscillator frequency of 3 030~4 350 MHz, and the intermediate frequency of 3 000 MHz. Compared to a single mixer, its linear performance was greatly optimized and was more suitable for high performance receivers.