This section provides an overview for bipolar transistors as well as their applications and principles. Also, please take a look at the list of 13 bipolar transistor manufacturers and their company rankings.
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A bipolar transistor is a three-terminal semiconductor device.
Also called a junction transistor, it consists of N-type and P-type semiconductors in a P-N-P or N-P-N junction structure. Unlike field effect transistors (FETs), which are unipolar transistors in which either holes or free electrons act as carriers, bipolar transistors are called bipolar because both holes and free electrons are involved in their operation.
The two main functions of bipolar transistors are amplification and switching.
In amplification circuits that turn minute signals into sufficiently large levels, bipolar transistors are more advantageous than unipolar transistors, especially when a high amplification factor is required. Bipolar transistors are also superior in operating at high frequencies.
For example, in power supply regulator circuits where switching noise with high-frequency components must be suppressed, there is a marked difference in noise rejection ratio and other characteristics between circuits using bipolar transistors and those using FETs.
Bipolar transistors are still used in small-lot production and high-frequency amplification circuits that are difficult to make into ICs, but because they are current-driven, they consume more power than unipolar transistors, which are voltage-driven. However, because they are current-driven, they consume more power than voltage-driven unipolar transistors.
On the other hand, switching circuits are used for ON/OFF control of current, but unipolar transistors are superior in terms of switching speed and miniaturization, so they are rarely used for this purpose.
Semiconductors can be classified into P-type and N-type semiconductors: P-type semiconductors are filled with holes, which are missing electrons; N-type semiconductors are filled with free electrons, which are in surplus.
Transistors are a combination of P- and N-type semiconductors. In the case of bipolar transistors, there are two types of transistors: one consisting of three regions: P-type, N-type, and P-type, and the other consisting of three regions: N-type, P-type, and N-type.
The former is called a PNP transistor and the latter an NPN transistor; the three regions are the emitter, base, and collector, each of which is connected to an electrode through which voltage is applied and a signal current flows. The base is characterized by being extremely thin.
The principle of operation of a bipolar transistor is explained using the example of an NPN-type transistor, which has an N-type semiconductor sandwiched between a P-type semiconductor.
With the emitter connected to the reference voltage (0V) and the collector connected to VCC (e.g. +5V), when a positive voltage is applied to the base and a base current Ib flows to the emitter, a current Ic of β × Ib flows from the collector to the emitter. This is the principle of amplification by a transistor, which is based on current amplification in bipolar transistors. β is called the current amplification factor and is usually around 100~200. In PNP transistors, the direction of the applied voltage and current is opposite, but the principle of amplification is the same.
In switching operation, a large base current Ib allows sufficient current to flow to the load connected to the collector. Also, if the base current is set to 0A, no current flows to the load. By flowing/not flowing the base current Ib, the current flowing to the load is turned ON/OFF and the switching operation is realized.
Type Names of Bipolar Transistors
Prior to 1993, the JIS standard stipulated how to name semiconductor components. Therefore, the application of a transistor can be determined to some extent from its type name. For Bipolar Transistors, the first three letters are as follows
The actual type name, for example, 2SA372Y, is composed of three letters followed by a number and an alphabet. The numbers start with 11 and consist of 2 to 4 digits, but they are assigned in the order of registration and have no meaning. The last alphabet means the rank classification of the amplification ratio.
This JIS standard was abolished in 1993, but has continued to be used in the standard "Type Names of Individual Semiconductor Devices" issued by the Japan Electronics and Information Technology Industries Association (JEITA), which succeeded it.
*Including some distributors, etc.
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WIN SOURCE is a customer-focused online store serving a wide variety of markets industries ranging from consumer to automotive to medical, industrial, and aerospace. WS specializes on size and speed, offering a catalog of over 1 million SKUS that can be shipped within 24 hours around the world. Offerings include an extensive array of semiconductor components, audio products, cable assemblies, racks, and battery products. WIN SOURCE is AS9120B, ISO9001, ISO14001, and ISO45001 certified and is a member of the anti-counterfeiting organization, ERAI.
Founded in San Clemente, California in 1997, NetSource Technology, Inc. is an independent stocking distributor of electronic components and global procurement services, providing comprehensive supply chain solutions to OEMs and contract manufacturers worldwide. NetSource Technology serves the aerospace, automotive, IoT, medical, mobile device, and telecommunications industries and related companies. NetSource Technology specializes in locating hard-to-find, obsolete, end-of-life and highly allocated components with long lead times, supporting customers throughout the complete supply chain lifecycle.
Hybrid Electronics is a global distribution specialist of electronic components, with access to over 50 million unique components. Among the markets HE serves are the aerospace, automotive, communications, defense, industrial, medical, national security, and test & measurement industries. In addition to components, HE also provides quality and compliance testing, counterfeit detection, upscreening, and other forms of quality control. Examples of component subtypes that HE offers include ICs, batteries, capacitors, semiconductor products, sensors, circuit protection, interconnectors, filters, optoelectronics, relays, switches, power supplies, and cables and cable assemblies.
Hello BOM is an online electronic component storefront designed to bridge customers and suppliers. Customers supply Hello BOM with their bill of materials (BOM) and Hello BOM uses smart analysis via AI data matching to quickly find precise matches that customers need. This is accomplished via Hello BOM’s growing component stock and product information database to grow increasingly accurate and fast, while also simplifying the process of R&D and purchasing for customers. Products include semiconductors, resistors, capacitors, diodes, inductors, connectors, transistors, and sensors.
ST Micro Electronics is a global semiconductor company serving customers with innovations to have a positive impact on people's lives. Their product line is micro electronic systems, such as switches, controllers, sensors and drivers. The main selling point of ST Micro Electronics is its provision of sustainable products, and introducing their electronics to create a more sustainable world. The company, as well as providing the electronic devices, also provides software and support, ensuring that all fields are covered to provide a fully provide a supported and strong relationship with their customer base. ST Micro Electronics believe that technology plays a key role in helping to solve environmental and social challenges, which is why their semiconductor technologies start with their employees, their customers and partners.
Toshiba Electronic Devices & Storage Corporation is a division of Toshiba focusing on providing designs for end-product developers as well as semiconductor and drive equipment for automotive, industrial equipment, green energy, and consumer and personal electronic devices. Toshiba’s storage products include cloud-scale and enterprise-level products, and PC hard drives. Semiconductor products include Si Cower devices, MOSFETs, IGBTs, IEGTs, isolators, solid state relays, power management and intelligent power ICs, diodes, bipolar transistors, microcontrollers, automotive devices, ICs for wireless communication equipment, general purpose logic ICs, radio-frequency devices, sensors, and linear image sensors.
Infineon Technologies AG (Infineon) is headquartered in Neubiberg, Germany. Infineon designs, develops, manufactures, and markets semiconductors and related system solutions worldwide. Infineon’s automotive segment produces microcontrollers, discrete power semiconductors, IGBT modules, industrial microcontrollers, power and radar sensor ICs, SiC diodes, MOSFETs voltage regulators, comfort electronics, infotainment, powertrain, and security products. Industrial Power Control segment provides bare dies, discrete IGBTs, and driver ICs among other components. Power & Sensor Systems segment offers gas and pressure sensors, MEMS microphone chips, control ICs, and GaN power switches among others.
Diodes Incorporated is a supplier for the consumer electronics, computing, communications, industrial, and automotive markets. Diodes Incorporated designs, manufactures, and supplies application-specific standard products in the discrete, logic, analog, and mixed-signal semiconductor markets worldwide. It focuses on low pin count semiconductor devices. Diodes specializes in semiconductor products, such as MOSFET, TVS, and performance Schottky rectifiers, transient voltage suppressors and other devices. It also provides analog products, such as power management devices comprising AC-DC and DC-DC converters, signaling devices, CMOS devices, and analog switches. Diodes Incorporated was incorporated in 1959 and is headquartered in Plano, Texas.
ROHM Semiconductor was incorporated in 1940 and is headquartered in Kyoto, Japan. ROHM manufactures and sells electronic components worldwide. ROHM operates through the segments ICs, discrete semiconductor devices, and modules. ROHM provides ICs comprising memory, amplifiers and linear, power management, clocks and timers, switches and multiplexers, logic, data converters, sensors and MEMS, display drivers, motor/actuator drivers, interfaces, communication and speech synthesis LSI, audio and video, and microcontrollers. ROHM also offers discrete semiconductor products include MOSFETs, bipolar transistors, and diodes; power devices, including power transistors and diodes, SiC power devices, IGBT, and IPM; passive devices, such as resistors, and conductive polymer and tantalum capacitors; and various modules among others.
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Derivation MethodThe ranking is calculated based on the click share within the bipolar transistor page as of March 2023. Click share is defined as the total number of clicks for all companies during the period divided by the number of clicks for each company.
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