信号衰减器基本上是一种四端器件,在某些情况下,其中两端可能是共用的。这种器件用于以精确的量值来降低信号电平,使得放大器和信号调节装置不致过激励(信号太大)而引起失真。与滤波器不同,衰减器具有平坦的响应,仅仅降低信号电平。图2.50说明这一点。 用于阻抗匹配型衰减器,通常,希望损耗最小;因此这种衰减器经常称为最小损耗衰减器。一种典型的应用是:把75Ω有线电视系统与50Ω频谱分析仪匹配起来。这种小盒的最简单类型是L形衰减器,这样称呼是因为该电路像字母“L”。 A signal attenuator is basically a four-terminal device, which in some cases may be common to both ends. This device is used to reduce the signal level by a precise amount so that the amplifier and signal conditioning are not overdriven (the signal is too large), causing distortion. Unlike filters, the attenuator has a flat response that simply reduces the signal level. Figure 2.50 shows this. For impedance matching type attenuators, it is usually desirable to minimize losses; such attenuators are therefore often referred to as minimum loss attenuators. A typical application is to match a 75Ω cable system to a 50Ω spectrum analyzer. The simplest type of box is the L-shaped attenuator, which is called because the circuit looks like the letter “L”.