Source of transistor and difference between NPN and PNP

History of Transistors

Reviewing History

Before sharing the NPN and PNP of transistors, let me share some basic knowledge.

Electronic tube

Before the emergence of transistors, there was a device with a function similar to that of a transistor, called an electron tube.

In 1904, the world's first electronic diode was born under the hands of British physicist Fleming.

Electronic tube is one of the earliest electronic signal amplification devices.

A cathode electron emission part, control gate, acceleration gate, and anode (screen) lead that is enclosed in a glass container (usually a glass tube) are soldered onto the tube base, and electronic modulation signals are injected into the control gate in vacuum using an electric field. Different parameter signal data after signal amplification or feedback oscillation are obtained at the anode.

Early transistor

Electronic tubes were used in early electronic products such as televisions and radio amplifiers. In recent years, they have gradually been replaced by amplifiers and integrated circuits made of semiconductor materials. However, in some high fidelity audio equipment, low noise and high stability electronic tubes are still used as audio frequency power amplifiers.

Circuit boards using early transistors

Advantages and disadvantages of electronic tubes:

Disadvantages: Large volume, high power consumption, severe heat generation, short lifespan, low power utilization efficiency, fragile structure, and the need for high-voltage power supply.

Advantages: Strong load capacity, superior linear performance to transistors, high operating frequency, and superior to transistors in high-frequency and high-power fields.

The volume of electrons is relatively large (compared to transistors). In 1946, the world's first computer was built using 1.8W electronic tubes, covering an area of 150 square meters, weighing 30 tons, and consuming approximately 150 kilowatts of electricity.

Ancient Computers

What Is a Transistor?

Transistors

Due to the many drawbacks of electronic tubes, humans have invented more advanced transistors than electronic tubes.

A transistor is a solid-state semiconductor device that includes diodes, transistors, field-effect transistors, thyristors, etc. It has various functions such as detection, rectification, amplification, switching, voltage stabilization, signal modulation, etc.

December 16, 1947: William Shockley, John Barton, and Walter Bratton successfully manufactured the first transistor at Bell Labs.

First transistor model:

First transistor model

Transistors, as a variable current switch, can control output current based on input voltage. Unlike ordinary mechanical switches, transistors use electrical signals to control their opening and closing, and the switching speed can be very fast, with a switching speed of over 100GHz in the laboratory.

Previously, I also shared a video with everyone on the working principle of transistors

Anyone who wants to watch the video can click on the link above.

The above video shows the basic working principle of transistors.

What Is a Triode?

Transistor

Triode, also known as semiconductor transistor, also known as bipolar transistor or crystal transistor, belongs to a type of transistor.

A transistor is a semiconductor device that controls current. Its function is to amplify weak signals into electrical signals with larger amplitude values, and it is also used as a contactless switch.

Triode

Triode is one of the basic semiconductor components, which has the function of current amplification and is the core component of electronic circuits. A transistor is a device that produces two PN junctions that are very close together on a semiconductor substrate. The two PN junctions divide the entire semiconductor into three parts, with the middle part being the base region and the two sides being the emitting and collecting regions. There are two types of arrangement: PNP and NPN.

NPN vs PNP Overview

Differences between NPN and PNP

N: Negative

P: Positive

There are two types of crystal transistors based on their materials: germanium tubes and silicon tubes. And each type has two structural forms: NPN and PNP, but the most commonly used are silicon NPN and germanium PNP transistors.

Different definitions

NPN type transistor: composed of two N-type and one P-type semiconductors, with P-type semiconductors in the middle and two N-type semiconductors on both sides. Triode is the most important device in electronic circuits, with its main functions being current amplification and switching.

PNP type transistor: A transistor composed of two P-type semiconductors sandwiched between one N-type semiconductor, hence it is called a PNP type transistor. It can also be described as a transistor in which current flows from emitter E.

Current Control Differences

Different current control

NPN: Use B → E current (IB) to control C → E current (IC). The E-pole potential is the lowest, and during normal amplification, the C-pole potential is usually the highest, i.e. VC>VB>VE

PNP: Control the current (IC) of E → C using the current (IB) of E → B. The E-pole potential is the highest, and during normal amplification, the C-pole potential is usually the lowest, i.e. VC<VB<VE

Output State Differences

Different output states

PNP and NPN type sensors actually utilize the saturation and cutoff of the transistor to output two states, belonging to switch type sensors. But the output signal is completely opposite, that is, high level and low level. The NPN output is low level 0, while the PNP output is high level 1.