Chapter 1 Diode circuits Objective To understand the diode operation and its equivalent circuits To understand various parameters of diodes Load line analysis Diode applications in rectifiers HWR,FWR Diode testing Zener diode Diode data sheets and specifications Diode applications in clipper circuits Numerical
Fig a semiconductor diode symbol
Fig b Vi characteristics of a diode n-type versus p-type n-type materials make the Silicon or Germanium atoms more negative. p-type materials make the Silicon or Germanium atoms more positive. Join n-type and p-type doped Silicon or Germanium to form a p-n junction. p-n junction When the materials are joined, the negatively charged atoms of the n-type doped side are attracted to the positively charged atoms of the p-type doped side. The electrons in the n-type material migrate across the junction to the p-type material electron flow .
the holes in the p-type material migrate across the junction to the n-type material conventional current flow . The result is the formation of a depletion layer around the junction.
Operating conditions No Bias
No bias condition No external voltage is applied VD 0V and no current is flowing ID 0A.
Only a modest depletion layer exists Reverse bias condition External voltage is applied across the p-n junction in the opposite polarity of the p- and ntype materials.