Why FET has high input impedance than BJT?

The input impedance of BJT is less than FET.

This is because FET uses reverse bias between gate and drain terminals that provide high input impedance. In the case of MOSFET, the high impedance Is provided by the oxide layer.

What makes FETs have high input impedance?

In FET the high input impedance was provided by the reverse bias of Gate and channel. But there was some minority current. This drawback of FET was corrected using MOSFET where an insulating oxide layer was inserted between the gate and substrate to increase the channel impedance.

Why is a FET better than a BJT?

Why is FET Preferred over BJT? Field-effect transistors provide high input impedance as compared with BJTs. The gain of FETs is lesser as compared with BJTs. The radiation effect of FET is less.

Which has higher impedance MOSFET or BJT?

BJTs tend to have better, more linear gain characteristics and can give you a lot higher voltage gain than MOSFETs. They're also able to handle higher output currents and have a lower output impedance.

What is the input impedance of FET?

The input impedance of an amplifier can be tens of ohms, (Ohms Ω) to a few thousand ohms, (kilo-ohms kΩ) for bipolar based transistor circuits up to millions of ohms, (Mega-ohms MΩ) for FET based transistor circuits.

Why the input impedance of JFET is greater than BJT?

Why the input impedance in JFET is very high in comparison with BJT?

BJTs offer smaller input impedances, meaning they draw more current from the power circuit feeding it, which can cause loading of the circuit. FETs offer greater input impedance than BJTs. This means that they practically draw no current and therefore do not load down the power circuit that's feeding it.

What is the difference between FET and BJT?

BJT and FET are electronic devices. The basic difference between BJT and FET is that the bipolar junction transistor is the bipolar and current control device, while FET (field effect transistor) is the unijunction transistor. It is a voltage control device.

Why the input impedance of MOSFET is higher than FET?

MOSFET has higher input impedance then JFET, since the gate terminal is isolated from the source by means of an insulating layer of Silicon Dioxide or some other suitable oxide, which supports a leakage current of extremely small magnitude.

Why FET is thermally stable than BJT?

More thermal stability. FET has a negative temperature coefficient at high current levels. It prevents the FET from thermal breakdown issue. In IC fabrication, BJTs are occupying more space.

Why FET is unipolar device?

FETs are also known as unipolar transistors since they involve single-carrier-type operation. That is, FETs use either electrons or holes as charge carriers in their operation, but not both. Many different types of field effect transistors exist.

Which of the following statement is true about a FET?

Which of the following statement is true about FET? Explanation: Because of the Sio2 insulator, doped between drain and source at the top, the resistance offered by this is very high. The insulator will stop the flow of electron from one part to another which acts as an open circuit.

What is the output impedance of FET amplifier?

The output impedance is simple the parallel combination of the Emitter (Source) resistor R_L and the small signal emitter (source) resistance of the transistor r_E. Again from section 9.3. 3, the equation for r_E is as follows: Similarly, the small signal source resistance, r_S, for a MOS FET is 1/ g _m .

What is the difference between BJT and JFET?

The JFET stands for junction field-effect transistor while BJT stands for the bipolar field-effect transistor. JFET is a unipolar device, BJT is a bipolar device. JFET is the low noise level, BJT is the high noise level.

Which configuration has highest input impedance in BJT?

The common collector, emitter follower offers a high input impedance and a low output impedance. The voltage gain is unity, although current gain is high.

Which of the following statement is true about FET common source amplifier compared to BJT amplifier?

8. Which of the following statement is true about FET common source amplifier compared to BJT amplifier? Explanation: FET due to its physical nature has very high input impedance; hence the voltage drop in input side will be very less making the entire signal to pass through the input port. 9.

Which configuration of JFET is mostly preferred?

FET, Field Effect Transistor Circuit Design Includes:

Both current and voltage gain can be described as medium, but the output is the inverse of the input, i.e. 180° phase change. This provides a good overall performance and as such it is often thought of as the most widely used configuration.

Why FET is called field effect transistor?

The concept of the field effect transistor is based around the concept that charge on a nearby object can attract charges within a semiconductor channel. It essentially operates using an electric field effect - hence the name.

What are the advantages of FET?

Why is noise less in FET?

FET is less noisy than BJT because FET is a unipolar device ( current is either due to holes or electrons) and BJT is a bipolar device ( current is due to both electrons and holes). Since, FET is a unipolar or majority carrier device and the temperature effect on it is less than BJT.

Which configuration of transistor amplifier has highest input impedance?

Answer. here's your answer! common collector, this is also known as emitter follower because the emitter voltage follows that of the base.