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RF Transistors Information

RF transistors are designed to handle high-power radio frequency (RF) signals in devices such as:

 

  • Stereo amplifiers
  • Radio transmitters
  • Television monitors

Like other semiconductor devices, they are made of materials such as silicon (Si) or germanium (Ge) and doped with impurities to induce changes in electrical properties.

 

There are several basic types of RF transistors:

 

  • Bipolar RF transistors: Consist of an N-type or P-type layer sandwiched between two layers of the opposite type. Both NPN and PNP configurations are available.
  • MOSFET RF: Metal-oxide field effect transistors (MOSFETs) with a channel made of either an N-type or P-type material.
  • Heterojunction field effect transistors (HFETs): Require a negative power supply and are used mainly for driver or power amplification applications.
  • Pseudomorphic high electron mobility transistors (PHEMTs): Used mainly in wireless devices and satellite communication systems. 

Specifications

 

RF Transistors Information Selecting RF transistors requires an analysis of performance specifications. Power gain, a measure of power amplification, is the ratio of output power to input power.

 

Noise figure, a measure of the amount of noise added during normal operation, is the ratio of the signal-to-noise ratio at the input and the signal-to-noise ratio at the output.

 

Both power gain and noise figure are expressed in decibels (dB).

 

Other performance specifications for RF transistors include:

 

  • Output power
  • Operating frequency
  • Operating temperature

Some RF transistors support a temperature range and feature mechanical and electrical specifications that are suitable for commercial or industrial applications. Other devices meet screening levels for military specifications (MIL-SPEC).

 

IC Package Types

 

Basic integrated circuit (IC) package types for RF transistors are:

 

  • Transistor outline (TO)
  • Small outline (SO)
  • Small outline transistor (SOT)

For each package type, many variants are available. Transistor outline packages include:

 

  • TO-92: A single in-line package often used for low power devices.
  • TO-220: Suitable for high power, medium current, and fast-switching power devices.
  • TO-263: The surface-mount version of the TO-220 package.

Small outline transistor packages include:

 

  • SOT23: Often used in home appliances, office and industrial equipment, personal computers, printers, and communication equipment.
  • SOT89: A plastic, surface mounted package with three leads and a collector pad for good heat transfer.
  • SOT223: An encapsulated package that provides excellent performance in environments with high temperatures and humidity levels.

IC package types that use flat packaging (FPAK) are also available.

 

Packing Methods

 

Packing methods for RF transistors consist of:

RF Transistors Information

  • Tape reel
  • Rail
  • Bulk pack
  • Tube technologies

The tape reel method packs components in a tape system by reeling specified lengths or quantities for shipping, handling, and configuration in industry-standard automated board-assembly equipment.

 

Rail, another standard packing method, is typically used only in production environments. Bulk pack devices are distributed as individual parts, while tray components are shipped in trays.

 

Typically, the tube or stick magazine method is used to feed bipolar RF transistors into automatic placement machines for through-hole or surface mounting.

 

Standards

 

ASTM E1855 - Standard test method for use of 2n2222a silicon bipolar transistors as neutron spectrum sensors and displacement damage monitors. 

BS EN 120003 - Specification for harmonized system of quality assessment for electronic components - blank detail specification - phototransistors, photodarlington transistors, phototransistor arrarrays. 

BS EN 62373 - Bias-temperature stability test for metal-oxide, semiconductor, field-effect transistors (MOSFET). 

IEC 60747-8-2 - Semiconductor devices discrete devices part 8: field-effect transistors section two - blank detail specification for field- effect transisitors for case-rated power amplifier applications. 

 

References

 

Image Credits:

 

MACOM | TT Semiconductor, Inc. | 1-Source Electronic Components

 


Related Products & Services

  • Bipolar RF Transistors

    Bipolar RF transistors consist of an N-type or P-type layer sandwiched between two layers of the opposite type. They are designed to handle high-power radio frequency (RF) signals in devices such as stereo amplifiers, radio transmitters, and television monitors.

  • Insulated Gate Bipolar Transistors (IGBT)

    Insulated gate bipolar transistors (IGBT) are bipolar transistors with an insulated gate. They combine the advantages of the bipolar transistor (high voltage and current) with the advantages of the MOSFET (low power consumption and high switching).

  • Metal-Oxide Semiconductor FET (MOSFET)

    Metal-oxide semiconductor field-effect transistors (MOSFETs) are electronic switching devices with a conducting channel as the output. An electrode called a gate controls the width of the channel and determines how well the MOSFET conducts.

  • Power Bipolar Transistors

    Power bipolar transistors are semiconductors in which a base n-type or p-type layer is sandwiched between emitter and collector layers of the opposite type. The junctions between the semiconductor sections amplify weak incoming electrical signals.

  • Power MOSFET

    Power MOSFETs are majority carrier devices which have high input impedance and do not exhibit minority carrier storage effects, thermal runaway, or secondary breakdown. Power MOSFETs have higher breakdown voltages than bipolar junction transistors (BJTs) and can be used in higher frequency applications where switching power losses are important.

  • RF MOSFET Transistors

    MOSFET RF transistors are metal-oxide semiconductor field-effect transistors (MOSFETs) that are designed to handle high-power RF signals from devices such as stereo amplifiers, radio transmitters, TV monitors, etc.

  • Small-Signal Bipolar Transistors (BJT)

    Small-signal bipolar transistors (BJT) are semiconductors that amplify small AC or DC signals. They consist of a base n-type or p-type layer sandwiched between emitter and collector layers of the opposite type.