Impatt Diode

Seminar on

IMPATT DIODE

Presented by

Barnasree GoswamiSection: b2

Class Roll no: 122University roll no: 10903061134

What is an IMPATT Diode?

IMPATT is an acronym of IMPact ionization Avalanche Transit-Time.

The IMPATT diode is a type of microwave negative conductance device that operates by a combination of carrier injection and transit time effects. They operate at frequencies between about 3 and 100 GHz or more.

They can be fabricated with Si, GaAs , InP or SiC.

Device Structure:

The device is an n+-p-i-p+ structure, essentially consisting of two regions-

i) the n+-p region in which avalanche multiplication occurs,And ii) the i (essentially intrinsic) region through which the generated holes must drift while moving to the p+ contact.

n+ p i p+

+ - h+ drift

LE(x)

x

Principle of Operation:

The device operates in a negative conductance mode i.e., when the a.c. component of current is negative over a portion of cycle where the a.c. voltage is positive and vice versa. The negative conductance occurs because of two processes which cause the current to lag behind the voltage in time-

i)A delay due to the avalanche process

ii) A further delay due to the transit time of carriers across the drift region.

Applications of IMPATT Diode:

The main advantage of IMPATT Diodes is their high power capability. They have a variety of applications in-

i) Low power radar systemsii) Alarmsiii) Microwave generatorsiv) Transmitters for millimeter wave communication

Specifications:

Parameter Range

Operating frequency 30 to 37 GHz

Minimum CW power 50 to 400 mW

Breakdown voltage 34 to 42 V

Operating Current 80 to 150 mA

Operating voltage (max) 10 V

Diode capacitance 1.3 to 2.0 pF

Package capacitance 0.2 pF

Thank You!