RF Transistors Information

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. 



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.




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. 




Image Credits:


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



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