HP HP-Bench-Briefs-1987-07-09 free download

File name HP-Bench-Briefs-1987-07-09.pdf

HEWLETT PACKARD SERVICE INFORMATION FROM HEWLETT-PACKARD 3rd Quarter 1987 A Few Fundarnentalls About Semiconductors The diode, one of the simplest of semiconductor devices, functions as a low-resistance conductor to current With Forward Bias nd Zener Diode flowing in one direction and as a virtually "open" conductor for current flowing in the opposite direction. Diodes are most commonly made by growing materials with p-type impurities on materials with n-type impurities to form what is known as a pn junction. These devices are said to be for- ward-biased when conventional cur- . * rent flows from the anode, or p-type material, across the junction to the Rectifiers-power diodes used Since the depletion region acts as cathode, or n-type material, with a primarily for power rectification in a dielectric between two conducting positive-voltage connected to the p- half-wave and full-wave bridge plates, the varactor acts as a capacitor r side and a negative voltdge connected to the n-side. (This is the same as saying that forward-biased electrons configurations. High-power rectifiers are usually packaged in metal cases to permit the rapid dissipation of whose capacitance value depends on the applied reverse voltage. TVs or radios may be tuned to flow easily from the cathode to the heat. channels or stations manually by anode.) Zener Diodes-designed for nor- turning a knob that changes the In the reverse- or backward-bias mal reverse-bias operation. This diode position of capacitor plates with re- condition with a positive voltage on is made so that when the voltage spect to one another. They use a the n-type material (cathode), diodes applied reaches a specified value, the manually altered air variable tuner. become good