Transistor as a Rectifier
  Transistor is a three terminal semiconductor device normally used as an amplifier or as a switch. Here the alternating current (a.c) rectifying property of the transistor is considered. The ordinary silicon diode exhibits a voltage drop of ~0.6V across its terminals. In this article it is shown that the transistor can be used to build a diode or rectify low current a.c (~mA) with a voltage drop of ~0.03V. This voltage is ~20 times smaller than the silicon diode. This article gives the half-wave and full-wave transistor rectifier configurations along with some applications to justify their usefulness. 
Raju Baddi
physics.gen-ph