Application Note

Introduction To Gunn Diodes

Source: e2v technologies
By e2v technologies

The Gunn diode is the best known and most readily available device in the family of transferred electron devices (TED). They are employed as DC to microwave converters using the negative resistance characteristics of bulk Gallium Arsenide (GaAs) and only require a standard, low impedance, constant voltage power supply, thereby eliminating complex circuitry.

The DC1200 series of GaAs Gunn diodes is designed for operation at fixed frequency (determined by the oscillator cavity) within a specified band under CW or pulsed conditions. Both conventional and hot electron injected (graded-gap) Gunn diode designs are available. All devices feature low FM and AM noise characteristics and their wideband negative resistance enables them to be used in voltage controlled and mechanically tuned oscillators. The hot electron injected Gunn diodes offer the additional advantages of:

  • higher fundamental frequency operation,
  • increased efficiency,
  • improved temperature stability,
  • improved turn-on characteristic and
  • reduced FM sideband noise

Devices are available in either polarity, but are generally supplied as negative heat sink.

Package Styles

Several standard package styles are offered covering the frequency range 4 to 110 GHz and designed to suit different applications. Custom packaging requirements will also be considered upon request.

The following package limitations need to be taken into consideration:

Thermal Resistance
The lowest thermal resistance is offered by the screw-based packages (outlines 40, 86 and 106). For high volume, lower power applications where oscillator assembly time is more important, non-threaded packages such as outline 00 will be preferred.

Frequency Range
The magnitude of the parasitic impedances attributed to the package element reduces with the package size (004864106). Consequently, the larger, more robust package styles are normally specified for operation at lower frequencies and the smaller, low parasitic impedance packages are recommended for the higher frequency applications.

Magnetically Tuned Circuits
For applications involving magnetically (YIG) tuned oscillators, Gunn diodes can be supplied in Kovar-free packages.

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