Digital current source is nonvolatile

摘要

Digitally programmable current sources that feature automatic trimming and retain the setting despite power-down cycles are useful in applications such as RF-and laser-communications drivers. The circuit in Figure 1 , for example, is particularly suited for setting the drive current for the optical pump in widely tunable VCSELs (vertical-cavity surface-emitting lasers). These lasers are suitable in systems using wavelength-agile DWDM fiber-optic communication links.