Types of Transistors Definition and Uses

Transistors Definition and Uses

 

Types of Transistors

A three-lead Transistors semiconductor device that functions as: an electrically controlled switch, or Transistors a current amplifier

Transistor is similar to a tap.

- Turning the tap's control knob changes the flow rate of the water coming out of the tap.

- A small voltage/current applied to the control lead of the transistor controls a large current flow

Through its other two leads.

Transistors

Transistor Types: BJT, JFET, and MOSFET

Types of Transistors

• Bipolar Junction Transistor (BJT)

- NPN and PNP

• Junction Field Effect Transistor (JFET)

- N-Channel and P-Channel

• Metal Oxide Semiconductor FET (MOSFET)

- decrease type (N- and P-channel) and increase type (N- and P-channel)

bj NPN and PNP.

- NPN: A small input current and a positive voltage @ applied to its base (with Vb>Ve)

Allows a large current to flow from the collector to the emitter.

PNP Transistors

 

PNP: a small output current and a negative voltage it's base (with VB0.6V)

NPN Transistors

An NPN. implemented based on

between transistor, pn junction

becomes base and emitter

Lean forward during the forward

bias, the escaping electrons are drawn

for a positive basis.

• Some electrons exit through

base, but because the p-type base

so thin, attack

The gain of electrons leaving the emitter is

very close to the collector side

that they jump

Collector. raising the base

The voltage increases the emitter-to-collector electron flow.

• Remember, a positive current is in flux

reverse direction

electron flow (current flow)

collector to emitter.

JFET Transistor

Junction field-effect transistors

• Junction field-effect transistors such as BJTs have three leading

semiconductor devices.

• JFETs are used to:

- electrically controlled switches,

- current amplifiers, and

- Voltage-controlled resistors.

• Unlike BJTs, JFETs do not require bias current and are controlled by

By using only one voltage.

• The JFET typically turns on when Vg - Vs = 0.

• When Vg - Vs0, the JFETs become resistant to current flow

Through drain-source pair “JFETs are depletion devices.

Types of JFET Transistors

• Two types of JFETs:

- N-channel and P-channel.

• In an n-channel JFET, a -ve voltage is applied to its gate (with VG < VS), which reduces the current

flowing from the drain to the source. It works with VD > VS.

• In a P-channel JFET, a +V voltage is applied to its gate (with Vg > Vs) to reduce the current

flowing from source to drain. It works with VS > VD.

• JFETs have very high input impedance and little or no input current

- If a circuit/component is connected to the gate of the JFET, no current is drawn

away from or drowned in this circuit.

MOSFET Transistor

Metal Oxide Semiconductor

• Metal Oxide Semiconductor FET.

• Similar to JFET.

A metal oxide insulator is placed at the gate to achieve high input impedance

door

- Gate input impedance approx. 1014Ω.

• The use of insulators as described above results in low gate-to-channel capacitance.

- If too much static electricity builds up at the gate, the MOSFET may be damaged.

MOSFET Type Transistor

• Enhancement Type:

- normally closed, thus when VG = VS

- the drain-source channel becomes short when the voltage applied to the gate causes Vg Vs

Resistance to current flow.

• Reduction Type:

- Normally, the maximum current thus flows through the drain-source channel is when Vg = Vs.

- The drain-source channel rises when the voltage applied to the gate causes Vg to VS

resistance to current flow

Read :- what-is-resistance