RF Diodes Information

RF Diodes Information

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

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. 

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• Understanding In-Line RF Power Measurements
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• AN721: Impedance Matching Networks Applied to RF Power Transistors, Courtesy of Motorola
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