了解RF巴伦及其转化功能

　　了解RF巴伦及其转化功能

　　巴伦（收缩平衡-不平衡）一二端口组件放置在电源与负载之间的差分平衡时，射频功能块必须连接到一个单一的结束，地面参考一。虽然它经常被“掩盖”的讨论，因为它没有射频RF信号链增加明显的价值，这在通常情况下的被动元件是必不可少的。

　　例如，需要一个单端功率放大器（PA）驱动偶极天线元件（平衡负载）或一个鞭天线（单端）馈送差动前端放大器。你可能熟悉的大众市场，低成本的巴伦用来连接一个屋顶，空中300Ω偶极子天线的广播电视到75Ω同轴电缆，然后连接到电视机本身（一些老电视假定偶极天线位于电视，所以只有一双300Ω，平衡螺丝端子输入，在这种情况下，一个平衡-不平衡将需要从同轴电缆电视输入使反变换）

　　However， the need for baluns extends beyond TVs and their antennas： in recent years， RF ICs are increasingly using differential configurations for their internal topology， because this provides improved noise immunity and better overall RF performance， and at a very-low-cost increment due to the nature of IC designs.

　　Baluns are not new or even relatively recent components. They have been used since the earliest days of wireless telephony to resolve the single-ended/balanced dilemma. Now， the growth in portable， handheld， and IoT applications means there is enormous demand for tiny， relatively low-power baluns. These can be constructed using ceramic-based fabrication similar to that used for bandpass filters， directional couplers， and SAW-type oscillators.