PIN DIODE

 

 WHAT  IS PIN DIODE?

                                           

                                                       

                                                      FIG. PIN DIODE

             

 

DEFINITION OF PIN DIODE:

  

It consists of a  layer of  N & P-type semiconductor material. In between them lightly dopped intrinsic layer is present, so it is called PIN diode.

SYMBOL OF PIN DIODE:

                             

PIN DIODE BASICS:

 

It is made up of a 3-layer P-type layer, I-type layer, N-type layer.

P-layer having holes as a majority carrier layer N-layer having electrons as majority carrier & I is an intrinsic layer means pure semiconductor layer.

because of additional I-intrinsic layer added in the PIN diode  offer high resistance.

It has a lower capacitance due to an intrinsic layer between the P & N-type layer.

P & N-type semiconductor material consists of either silicon or gallium arsenic material.

When adding I-layer then distance increase & capacitance decrease  

PIN diode act as a low-frequency rectifier.

PIN  DIODE CHARACTERISTICS:

1.LOW  CAPACITANCE:

By adding an Intrinsic layer in between P-N type layer then the distance between two layers are increase & capacitance decrease. Hence, lower capacitance.

2.HIGH BREAKDOWN VOLTAGE:

Due to an additional intrinsic layer in between P & N. Hence, reverse breakdown voltage increase.

3.CARRIER STORAGE:

Because of the  intrinsic layer in between P & N. Charge carrier which are due to P & N-type material that can be stored in the intrinsic layer.

Under zero & reverse-biased  PIN diode  has a very high impedance at uwave frequency & low impedance for small forward current.

At higher frequency PIN diode act as a variable resistance.

FIG.(d) CONSTRUCTION OF PIN DIODE      

 

OPERATION:

 

1. ZERO BIAS:  

                     

                                     FIG. ZERO BIAS

In zero bias Battery is not connected to the PIN diode.

The depletion region is present in between Intrinsic layer & N-type layer. electrons & holes charge carrier in intrinsic layer is store in between P & N-type layer.

 2. FORWARD BIAS:

In forward bias condition of  PIN diode  +ve  terminal of the battery is connected to anode &  -ve terminal of the battery is connected to cathode then depletion region in between intrinsic layer & N-type layer start to decrease the depletion region.

After cancelling the depletion region start the flow of current.

In forward bias PIN diode work as a variable resistance.

The depletion region decreases then resistance decrease.

Small resistance in the range 1 ohm to 10 ohm

so, PIN diode act as an ON state in the other word, the switch is ON