Programmable mixed signal devices optimize fibre-optic links

Obtaining the optimum, by way of performance, from fibreoptic communication s links requires a laser diode controller that, as well as providing useabl e light output over the operating temperature range, must also be able to h andle variations in components, laser diode parameters from device to devic e and problems of drift. This feature discusses the design of a laser contr oller that has, at its heart, a digitally controlled potentiometer. As the resolution of digital potentiometers moves from the 256 tap version used in the application described here to the new 1024 tap devices, it raises the question, are they an analogue or digital component?.