Using the p-i-n diode

The p-i-n (or PIN) diode is a semiconductor diode that contains a region of almost intrinsic (i-type) semiconductor between the p-type and n-type regions. The depletion layer associated with the p-n junction is entirely contained within the i-type region in the p-i-n structure. At low signal frequencies the diode behaves similarly to anormal p-n junction, but at high frequencies it exhibits a variable resistance. The p-i-n diode is used extensively as a modulator and switch in microwave systems.