Explain the operations of BJTs and CMOS transistors. What are the similarities a

Question

Explain the operations of BJTs and CMOS transistors. What are the similarities and differences between NPNs, PNPs, PMOS transistors, and (although never used in lab) NMOS transistors? How do their common source/emitter amplifiers have gain? Explain the concept of operating point and how it is achieved with a common emitter amp, common source amp, and the op amp-based amplifiers (differentiator, integrator, inverting, and non-inverting amplifiers). Roughly what should be the operating point, or at least operating range, in all of these cases, and why? How does operation change between single and dual supplies?

Explanation / Answer

BJT stands for Bipolar Junction Transistor.Bipolar means two types of carriers. 2 p-n junctions are available in BJTs.

Transistor means Transfer+Resister. Current is transferred from low resistance circuit to high resistance circuit.

BJT is a 3 terminals namely emitter, base and collector having 2 p-n junctions side by side which is used for amplifying the signal.

there are two types of BJTs 1)pnp 2)npn

basically emitter is heavily doped, the base is lightly doped, the collector is moderately doped. In normal operations

1)Emitter-base junction is forward biased

2)collector-base junction is reverse biased.

Biasing of BJT:

Biasing: In the connection of some D.C voltage sources, resistors and capacitors and transistors circuit to train the operating point or quotient point so that faithful amplification occurs at the output of the transistor.

need for biasing:

1) To keep the transistor in an active region. An active region is only the amplifying characteristics.

2) To set proper collector current for zero input signal.

3)To give the stability of the circuit output against temperature changes and Beta variations.

BJTs having high currents and resulting high power consumption so we go for Metal Oxide Semiconductor Device Field Effect Transistor in shortcut MOSFET.

MOSFETs having low currents and resulting low power consumption compared with BJTs.

The main difference between BJTs and MOSFETs are speed. BJTs having high speed of operation but MOSFETs are low speed compared with BJTs.

there are two types of MOSFETs namely N-MOS and P-MOS.

FETs having also 3 terminals source, gate, drain

In fets, there is a channel between source and drain. the current passing from the source to drain

operating point is same as explained in the BJTs part as maintaining the amplifying the input signal.

an op-amp is an operational amplifier which has very high open loop gain, infinite input resistance, low output resistance, Infinite bandwidth, zero offsets, infinite Common Mode Rejection Ration and high slew rate.

op-amp having inverting and non-inverting terminals so we can feed 2 input voltages the gain depends on the difference between these two input voltages.while single input voltage is given to BJTs and MOSFETs.

the opertaing range of op-amp is same as BJTs and MOSFETs.To maintain the circuit stability.

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