sufficient energy strikes the diode, it creates an electron-hole pair. These electrons and holes are swept across the p-n junction by the electric field created by reverse voltage before recombination takes place and in turn generates photo current. A solar cell, also known as photovoltaic cell, works on the principle of photovoltaic effect. Accordingly, the p-n junction of the solar cell generates emf when solar radiation falls on it.
. A bipolar junction transistor (BJT) is a semiconductor device and there are two types in that: NPN and PNP. SUM MA R Y - - - - - - - - Unit electronics and Communication A BJT can be operated in three different configurations: Common base, common emitter, common collector. The forward current gain in common base configuration α gives the ratio of the collector current to emitter current.
The forward current gain in common emitter configuration β gives the ratio of the collector current to the base current The BJT connected in common emitter configuration can be used as an amplifier. There exists a phase reversal of between the input signal and the amplified output signal. A transistor amplifier combined with a tank circuit and positive feedback acts as an oscillator The logic gates are logical circuits providing output only for a combination of inputs. De Morgan’s First theorem states that the complement of the sum of two inputs is equal to the product of its complements.
The second theorem states that the complement of the product of two inputs is equal to the sum of its complements. The basic elements required for the transmission and reception of a signal through long distance communication using electromagnetic waves are transducer, amplifier, carrier signal, modulator, power amplifier, medium of transmission, transmitting and receiving antenna, demodulator, detector. For long-distance transmission, the baseband signal is modulated with the carrier wave. If the amplitude of the carrier signal is modified with the instantaneous amplitude of the baseband signal then it is called amplitude modulation.
The frequency of the carrier signal is modified with the instantaneous amplitude of the