Advantages of fet over bjt
In This post we are going to learn about what are the advantages and disadvantages of FET over transistor.
Advantages of fet
An advantage of the FET is its high gate to main current resistance of the order of 100 MΩ or more, thus ensuring a high degree of isolation between control and flow.
Since base current noise will increase with training time, a FET typically produces less noise than a bipolar transistor (BJT) and is thus found in noise-sensitive electronics such as tuners and low noise amplifiers for receivers VHF and satellite main advantage of fet.
Second advantage of fet, It is relatively immune to radiation. It does not show any compensation voltage to zero drain current and therefore makes an excellent signal helicopter.
It usually has better thermal stability than a BJT. Since they are controlled by the gate gate, once the gate is closed or open, there is no extra power draw, as with a bipolar junction transistor or non-latching relays in some states.
This allows extremely low power switching, which in turn allows for a larger miniaturization of circuits because the heat dissipation needs are reduced compared to other types of switches.
Disadvantages of FET
It has a relatively low bandwidth product compared to a BJT most disadvantages of fet.
The MOSFET has the disadvantage of being highly susceptible to overloading voltages, thus requiring special handling during installation.
The frail insulating layer of the MOSFET between gate and channel makes it vulnerable to electrostatic discharge or to change the threshold voltage during handling such a disadvantages of fet.
This is usually not a problem after the device has been installed in a properly designed circuit.
FETs often have a very low resistance and high strength. However, intermediate resistances are significant, and so FETs can dissipate large amounts of energy during switching.
Thus, efficiency can put a premium on rapid switching, but this can cause transients that can excite street inductances and can generate significant voltages that can couple to the gate and cause unintentional switching.
FET circuits may therefore require a very careful look and may involve switching between switching speed and power dissipation.
There is also a compromise between nominal voltage and “on” resistance, so that high voltage FETs have a relatively high resistance and hence conduction losses.
Advantages of fet over bjt in tabular form
|1||Uni polar Device||Bipolar device|
|2||Voltage Controlled device||Current control device|
|3||High input impedance||low input impedance|
|4||better thermal stability||low thermal stability|
|5||high switching speed||low switching speed|
|6||less noisy||more noisy|
|7||easy to fabricate||difficult to fabricate on IC|
USE of FET
The most commonly used FET is the MOSFET. CMOS process technology (complementary metallic semiconductors) is the basis for modern integrated digital circuits.
This process technology uses an arrangement in which the MOSFET (usually ‘modulation mode’) MOSFET and n-channel channel are connected in series, so when ON, the other is off.
In FET, electrons can circulate in both directions through the channel when operating in linear mode. The convention for naming the drain terminal and the source terminal is somewhat arbitrary because the devices are built (but not always) symmetrically built from source to drain.
This makes the FETs suitable for switching analog signals between paths (multiplexing). With this concept, for example, a solid mixing plate can be constructed.
A common use of FET is like an amplifier. For example, due to high inlet strength and low exit strength, it is effective as a buffer solution in the usual drainage configuration.
IGBTs are used to switch the internal combustion engine ignition coils, where fast switching and voltage blocking capabilities are important.