Why do we use PNP?

Why do we use PNP?

The benefit of using a PNP is that the load only connects to the source when it is switched on. In contrast, one side of the load is always connected to the source when an NPN switches it on and off. In the measurement field, the PNP/NPN issue most often arises in the use of industrial sensors.

When H parameters are specified for a particular transistor The operating point is usually given Why is this necessary?

There are two main reasons for using h param- eter method in describing the characteristics of a transistor. Firstly, it yields exact results because the inter-effects of input and output circuits are taken into account. Secondly, these parameters can be measured very easily.

When PNP transistor is used as an amplifier?

When NPN transistor is used as an amplifier, majority charge carriers electrons of N-type emitter move from emitter to base and than base to collector.

What is PNP junction?

A PNP transistor is a bipolar junction transistor constructed by sandwiching an N-type semiconductor between two P-type semiconductors. A PNP transistor has three terminals – a Collector (C), Emitter (E) and Base (B). The PNP transistor behaves like two PN junctions diodes connected back to back.

Why NPN is preferred over PNP?

The majority charge carriers in an NPN transistor are electrons and the majority carriers in a PNP transistor are holes. The electrons have better mobility than holes. Therefore, NPN transistors are preferred over PNP transistors.

Is PNP sinking or sourcing?

PNP sensors are sometimes called “sourcing sensors” because they source positive power to the output. NPN sensors are sometime called “sinking sensors” because they sink ground to the output. The term “load” identifies the device the sensor powers.

Why we use H parameters?

H parameters are useful in describing the input-output characteristics of circuits where it is hard to measure Z or Y parameters (such as in a transistor). The problem can instead be solved by using hybrid parameters (i.e. h parameters).

What are the advantages of H parameters?

Advantages of h-parameter:

  • Easy to measure.
  • Convenient to use in circuit analysis and design.
  • Real numbers at audio frequencies.
  • Can be obtained from the transistor static characteristics curves.
  • Most of the transistor manufacturers specify the h-parameters.

When transistor is used as an amplifier then?

To use a transistor as an amplifier, its input must be forward biased and output must be reversed biased. So, emitter-base junction must be forward biased and collector-base junction must be reverse biased.

What is meant by CE amplifier?

Common Emitter as an Amplifier is a configuration of the basic Bipolar Junction Transistor (BJT). When emitter is made common to both input and output then it becomes Common Emitter Transistor.

What is forward bias?

Biasing is such an arrangement made in the PN junction device so that the device allows the flow of larger current in one direction. The device is said to be forward biased if the anode is connected to the positive end and cathode is connected to the negative end of the battery.

Is PNP forward bias?

Construction of PNP Transistor: The emitter and base junctions are forward biased, while the collector and base junctions are reverse biased. The forward biased emitter attracts electrons to the battery, causing current to flow from the emitter to the collector.

What is the use of h parameters?

H parameters are useful in describing the input-output characteristics of circuits where it is hard to measure Z or Y parameters (such as a transistor ). H parameters encapsulate all the important linear characteristics of the circuit, so they are very useful for simulation purposes.

What is the h-parameter of a transistor?

Parameters h fe is the most important small signal parameters of a transistor and is called small signal , indicated by ‘ (as already defined earlier). Figure 2 gives the h-parameter model for a transistor in CE configuration. Assuming sinusoidal voltages and currents, rms value I b, I c, V b and V c have been used.

How to draw h parameter equivalent network of a two port network?

To draw h parameter equivalent network of a two port network, first we have to write the equation of voltages and currents using h parameters. These are: Equation (i) can be represented as a circuit based on Kirchhoff Voltage Law: Equation (ii) can be represented as a circuit based on Kirchhoff Current Law:

Is the model of equation (3) valid for PNP transistors?

The model of Equation (3) and the corresponding equations are valid for both PNP and NPN transistors and are independent of the load impedance of the method of biasing. Figure 3 gives the h-parameter models for the transistor in CB and CC configurations.