JFW Introduction

An attenuator is an electrical component that reduces the amplitude of a signal passing
through it without significantly degrading the integrity of that signal. In a programmable
or step attenuator, the attenuation is controlled externally by an external analog or
digital signal, either manually or via a computer. Depending on the model, the maximum
attenuation ranges from 0 dB to 127 dB, in steps as small as 0.1 dB. The attenuator is
controlled by a combination of digital inputs, an analog voltage or via USB, RS-232, Ethernet
or GPIB. These devices are bi-directional, so either port can act as an input or an output.

JFW produces many programmable attenuators and attenuator systems for different
applications. This article will review the key components of a programmable attenuator
system and discuss the best choices for some common applications. Figure 1 shows several
JFW programmable attenuators.