generally bjt is faster than fets...because of many intrinsic junction capacitances between ...source and drain and bulk and gate,,,..
but now a days due to advancement in scaling fet is reduced in size sooo much that it became faster than bjt...
mosfet is faster because of scaling. small channel length. even though it is slower but distance to be travelled is less
BJT
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.
cause MOSFET are mainly the comes into category of Semiconductors, main work of inverter is to switch the contacts within microseconds, here i want to give some constructional things so it could go easy to understand the things, 1] MOSFET has a three satates, i]Deplition ii]enhancement iii]pick When the current go through the system the work of 'mft' has start as a implementing the depletion region(increasing the electrons in emitter collector junction) as and as the supply gets interrupted the MOSFET comes into work within our thinking due to high electrons consumption it goes extream fast switch the signal from one state to anther, actually MOSFET needs cery deep explination to understand it. but the main purpose is to stop reverse impulses and quike switching from one state to another.
So as opposed to a BJT transistor (which has a large but measurable input impedance) a Mosfet has even larger (presumably infinite) impedance. The reason is because of a small non-conducting zone that exists between the Gate side and the Drain-Source side. It acts as a small capacitor (which capacitors have infinite resistance), and the electromagnet field produced is what drives current between Source and Drain. Now, why is this desirable? In the case of BJT's there is a small current that flows into the base, essentially drawing small but existent power from the circuit connected at the Base. It is more ideal to have a transistor that completely separates the current of the control circuit and the current in the circuit being switched/supplied. Simply, it means its more efficient. When BJT transistors are turned off, power is still being used. The same isn't necessarily true for Mosfet transistors.
A: Initially the construction of an FET closely resemble the double diffused bipolar epitaxial transistor Both begins with an n+ substrate n- forming a 4 layer structure. another distinguishing feature is the electrical bonding of the upper most n+ diffusion [source] however with this bonding a parasitic diode in parallel cathode drain to source fortunatelly by virtue the polarity operation is unaffected. All in all FET have higher power, higher voltage rating practically no thermal runaway and a greatly inhibited secondary breakdown characteristics
Because of its much higher input impedance. When measuring voltage, that makes the voltmeter appear to the circuit as if it's not there, so the presence of the voltmeter doesn't change the operation of the circuit.
supposed to be MOSFET. but i also depends on your working freq.
A MOSFET (metal oxide semiconductor field effect transistor) can be used INSTEAD of a BJT (bypolar junction transistor, so transistor is redundant in your question), if the circuit in question is modified to allow it and the MOSFET is chosen appropriately. BJT's will usually have a higher intrinsic gain, but have lower input resistance. Also a BJT in general will work better at higher frequencies than a MOSFET (unless you choose a high frequency MOSFET) due to the capacitive nature of MOSFETs.
actually I prefer a bjt
1-BJT is bipolar while JFET is unipolar. 2-BJT has low input impedence while JFET has high input impedence. 3-JFET has low power discipation as compared to BJT. 4-JFET has low noise as compared to BJT. 5-BJT is current controlled while JFET is voltage controlled. 6-JFET is mostly used in digital circuits.
either field effect (JFET, MOSFET) or junction (BJT) or point contact (usually considered obsolete)either small signal or high powereither electron majority carrier (N-channel FET, NPN BJT) or hole majority carrier (P-channel FET, PNP BJT)either linear (used in amplifier and oscillator circuits) or switching (used in digital logic circuits)etc.
Advantages:- 1- mosfet are small compare to bjt's so it fabricated easily and space saving scheme on the ic's 2- mosfet's input impedance are very high so they do not load the circuits. loading effect doesn't arise. 3- operating frequency is very high so may be used at higher frequencies. 4- used in digital circuits for it's reliability. 5- effect of noise is less than bjt. so high signal to noise ratio. 6-mosfets are unipolar devices so reverse saturation current doesn't exist. 7- it consume less D.C power rather than BJT. Disadvantages:- handling is not easy- Mosfet is very sensitive to electrostatic charge so it may be destroy when you touch the pins of a mosfet devices by hand. trans conductance is low than BJT.
either field effect (JFET, MOSFET) or junction (BJT) or point contact (usually considered obsolete)either small signal or high powereither electron majority carrier (N-channel FET, NPN BJT) or hole majority carrier (P-channel FET, PNP BJT)either linear (used in amplifier and oscillator circuits) or switching (used in digital logic circuits)etc.
Yes
Advantages:- 1- mosfet are small compare to bjt's so it fabricated easily and space saving scheme on the ic's 2- mosfet's input impedance are very high so they do not load the circuits. loading effect doesn't arise. 3- operating frequency is very high so may be used at higher frequencies. 4- used in digital circuits for it's reliability. 5- effect of noise is less than bjt. so high signal to noise ratio. 6-mosfets are unipolar devices so reverse saturation current doesn't exist. 7- it consume less D.C power rather than BJT. Disadvantages:- handling is not easy- Mosfet is very sensitive to electrostatic charge so it may be destroy when you touch the pins of a mosfet devices by hand. trans conductance is low than BJT.
It helps us to select the Q - point of the BJT, MOSFET etc.
BJT(Bipolar junction Transistor)-It is bipolar device -meaning both electron and holes are responsible for conduction.-It is mainly used for amplification and switching purposes.-It is current controlled device.MOSFET(Metal Oxide Semiconductor Field Effect Transistor)-It is unipolar device -meaning only one of the charge carriers is responsible for conduction.-It has very high input resistance.Due to this reason it is used in initial stage of Operational amplifier.-It is voltage controlled device.
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.