A Sensor is a device that detects events or changes in quantities and provides

a corresponding output

Operation with reverse bias

Capacitance should be

small

Leakage current should be low

In form of IC’s

Thin silicon wafer

thousands of devices can be fabricated

Most popular are AD590 and LM35

Basic principle

VOLTAGE OUTPUT TEMPERATURE SENSORS

Need a source of power supply

Effective linear output

Low output impedance

CURRENT OUTPUT TEMPERATURE SENSORS

High output impedance

Need a input voltage source

Constant current regulators

DIGITAL OUTPUT TEMPERATURE SENSORS

o Fabricated with analog to digital convertor on an IC chip

o Doesn’t provide a standard digital surfaces

o Cannot be employed with standard measuring devices

RESISTANCE OUTPUT TEMPERATURE SENSORS

Typical semi conductor manufacturing equipment

Offers high tolerance to iron migration

Needs extra care

DIODE TEMPERATURE SENSORS

Uses regular PN junction diode

Very cheap and very efficient

Provides temperature coefficient of around 2.3 mV/°C

a. Absolute Pressure Sensor

b. Differential Pressure Sensor

c. Gauge Pressure Sensor d. Negative pressure sensor

The possibilities of applications of the semiconductor sensors are endless.

Research is still going on, almost all the sensors employ the use of semiconductors,

thus called semiconductor sensors.

From a Remote control television to satellite sensing everything involves semiconductor

sensors