BJT is a current controlled device because its output current is dependent upon the current in the base while for FET it is controlled by the voltage at the gate terminal of the transistor. BJT is a current controlled device because its base current is not zero while for a FET the gate current is zero
Forward saturation in a BJT occurs when the ratio of collecter-emitter current and base-emitter current reaches hFe or dc beta. A that point, the BJT is no longer operating in linear mode.
UJT is the voltage controlled device.in which only one mejority carriers are responsible for current flowing. UJT is one junction transistor and it is three terminal emitter and two base. BJT is the current controlled device. in which both mejority and minority carrier are responsiblefor current flowing. this type of transistor consists of two junction and three terminal these are : emitter , base , collector.
The base-emitter voltage of a BJT is dependent on temperature and current. The minimum voltage ranges from 0.6V to 0.7V. Anything less, and the transistor goes into cutoff. As far as "proper voltage" is concerned, it is more correct to say "proper current", because that is the basis for the BJT - it is a current amplifier, not a voltage amplifier. The proper current depends on the particular biasing design of the circuit at hand.
BJT is Bipolar junction transistor FET is Field effect Transistor It is a current controlled device It is voltage controlled device
BJT is a current controlled device because its output current is dependent upon the current in the base while for FET it is controlled by the voltage at the gate terminal of the transistor. BJT is a current controlled device because its base current is not zero while for a FET the gate current is zero
Because the operation of the transistor is determined by the current at the base. the principle equations of BJT operation are: Ic = h*Ib ,and Ie=Ib+Ic thus device operation is controlled by the input current.
for a BJT to amplify we give input signalif suppose we use BJT in CE configuration input is given at Emitter-Base junction and output is taken at Collector base junctionthe input voltage increases or decreases the forward bias of the E-B junction affecting a change in the base current and we know that collector current is a function of base current collector current also variesso by selectively changing the base current we can effectively change the collector current
Forward saturation in a BJT occurs when the ratio of collecter-emitter current and base-emitter current reaches hFe or dc beta. A that point, the BJT is no longer operating in linear mode.
The collector current is a multiple of the base current due to the inherent design of the BJT. In circuit analysis, barring knowing the exact amplification, I've used 50 many times - so if you have 20 uA flowing in the base, the collector current should be ~ 1mA, and the emmiter will be ~1.02mA.
Bipolar junction transistor(BJT)
The Self Bias of the BJT is also called the voltage divider bias. It is called thus because it can stabilize the collector current, the base emitter voltage and the amplification factor.
UJT is the voltage controlled device.in which only one mejority carriers are responsible for current flowing. UJT is one junction transistor and it is three terminal emitter and two base. BJT is the current controlled device. in which both mejority and minority carrier are responsiblefor current flowing. this type of transistor consists of two junction and three terminal these are : emitter , base , collector.
FET's (field effect transistors) are unipolar devices because unlike BJT's that use both electron and hole current, they operate only with one type of charge carrier. BJT is a current-controlled device; that is the base current controls the amount of collector current. FET is a voltage-controlled device, where voltave between two of the terminals (gate and source) controls the current through the device. BJT's have a low input impedance ( ~1k -3k ohms), while FET's have a very high input impedance (~10^11 ohms). Consequently FET's have a lower power consumption. BJT's produce more noise than FET's . FET's have a slower switching speed . BJT's are subject to thermal runway while FET's are immune to this problem. BJT's have a higher cutoff frequencey and a higher maximum current then FET's. FET's are easy to fabricate in large scale and have higher element density the BJT's.
transistor is a current controlled device. as the current flows through the base of the transistor , it works like a close switch.
The base-emitter voltage of a BJT is dependent on temperature and current. The minimum voltage ranges from 0.6V to 0.7V. Anything less, and the transistor goes into cutoff. As far as "proper voltage" is concerned, it is more correct to say "proper current", because that is the basis for the BJT - it is a current amplifier, not a voltage amplifier. The proper current depends on the particular biasing design of the circuit at hand.
An advantage of JFET is stable high current operation. A disadvantage of JFET is low capacitance. An advantage of BJT is constant voltage operation. A disadvantage of BJT is low thermal conductance.