资 源 简 介
RF Attenuators： For When You Have Too Much of a Good Thing
更高的信号电平通常是一个好东西在RF电路。它们会导致增加的信号-噪声比（SNR），并减少由内部电路元件噪声和外部信号噪声所造成的问题。其结果是，更高的信号电平一般简化了许多挑战的RF电路设计。
然而，在许多系统中，RF信号可以不可避免地具有宽的动态范围，跨越30，40，或更多的分贝，一些设计必须处理的信号具有超过100分贝的范围内。例子包括雷达或远程无线，甚至短程局域网，其中一个或两个链路节点移动和有障碍和干扰。
If a system is designed to funcTIon properly with lower-level signals， it may not have the headroom for the higher-power signals （in RF， power and signal level are usually closely correlated）。 The result is overload， saturaTIon， and even possible damage to sensiTIve analog components such as front-end amplifiers. Even if there is no permanent damage， the system cannot funcTIon properly as long as elements of the signal chain are “maxed out.” In these cases， it may take a relatively long time for the components to come out of saturation so that the signal chain is once again viable. In other cases， the attenuator matches the maximum value of a signal at one point to the more-limited maximum of another stage in the chain.
