RF diodes are designed to handle high-power radio frequency (RF) signals in stereo amplifiers, radio transmitters, television monitors, and other RF or microwave devices. There are many different types of products. PN junction diodes or general purpose diodes are designed for general-purpose applications. Schottky barrier diodes (Schottky diodes, Shottky diodes) are used mainly in high-frequency and fast-switching applications. By contrast, PIN diodes are used as either switches or attenuator elements. Varactor diodes can be used in electronic tuning systems to eliminate the use of and need for moving parts. Step-recovery diodes are designed for very high frequency (VHF) and fast-switching applications. Tunnel diodes and Gunn diodes are used in oscillators and other RF applications. Impact ionization avalanche transit-time (IMPATT) diodes are also designed to operate very high frequencies. Typically, these RF diodes are used as elements in either RF or microwave devices.
Specifications for RF diodes include forward voltage, maximum allowable reverse voltage, reverse current, repetitive peak reverse voltage, maximum reverse voltage, peak forward surge current, power dissipation, operating frequency, terminal capacitance, and junction operating temperature. Diode application is also an important consideration. Typically, RF diodes are categorized as amplification diodes, detector diodes, mixer diodes, damper diodes, limiter diodes, switching diodes, microwave diodes, or modulation diodes. Application requirements determine the proper selection of a detector diode, RF mixer diode, RF damper diode, limiter diode, switching diode, microwave diode, modulation diode, or amplification diode. Microwave diodes, microwave switching diodes, microwave damper diodes, and microwave diode arrays may include special features.
IC Package Types
RF diodes use many different IC package types. Examples include: diode outline (DO), small outline diode (SOD), transistor outline (TO), small outline transistor (SOT) discrete package (DPAK), and metal electrode leadless face (MELF). DO-4, DO-5, DO-8, DO-9, DO-15, DO-27, DO-34, DO-35, DO-41 and DO-201 are diode outline (DO) packages. SOD-80, SOD-106, SOD-123, SOD-323, and SOD-523 are small outline diode (SOD) packages. TO-3, TO-66, TO-92, TO-202, TO-220, TO-237 and TO-247 are transistor outline (TO) packages. SOT23, SOT26, SOT89, SOT143, SOT223, SOT323, SOT343, SOT346, SOT353, SOT363, SOT416, SOT457, and SOT523 are small outline transistor (SOT) packages. MELF packages for RF diodes include QuadroMELF, MicroMELF, and MiniMELF. D2PAK is a large surface-mounted package that includes a heat sink. SC-59, SC-74, and SC-76 are plastic, surface-mounted packages with three leads.
Related Products & Services
Diode arrays are composed of multiple discrete (usually unconnected) diodes on a single silicon chip. Diode arrays are important semiconductor products because they save assembly time and improve reliability over individually packaged diodes. In general, diode arrays use four or more diodes in a single package.
Diodes are electronic components that conduct electric current in only one direction, functioning as a one-way valve. Diodes are manufactured using semiconductor materials such as silicon, germanium or selenium and are used as voltage regulators, signal rectifiers, oscillators and signal modulators / demodulators.
PIN diodes are three-layer semiconductor diodes consisting of an intrinsic layer separating heavily doped P and N layers. The charge stored in the intrinsic layer in conjunction with other diode parameters determines the resistance of the diode at RF and microwave frequencies.
Power diodes are used mainly in high-power applications. They are built with large P-N junctions in order to pass large amounts of current and dissipate large amounts of heat.
Transient Voltage Suppressor Diodes (TVS)
Transient voltage suppressor (TVS) diodes are designed to limit over-voltages. They can dissipate high amounts of transient power in a short period of time.
Tunnel diodes are heavily doped P-N diodes in which electron tunneling from the conduction band in the N-type material to the valence band in the P-type region produces a region of negative resistance. This negative-resistance region is the most important area of operation. As the voltage is increased, the current decreases. This feature makes tunneling diodes especially useful in oscillators and radio frequency (RF) applications.
Varactor diodes are p-n junction diodes that are designed to act as a voltage controlled capacitance when operated under reverse bias.