A step recovery diode (SRD) is a semiconductor junction diode with the ability to generate extremely short pulses.
A step recovery diode can be referred to as a part of the microwave diode (during the high-frequency range, it tends to generate pulses).
The silicon step recovery diode has a variety of applications in microwave (MHz to GHz frequency range) electronics as pulse generator or parametric amplifier.
These diodes are dependent on the type of diodes that have the characteristics of turning-off fast based on their operation.
Quite recently we caught a bunch of SemiGen’s SSR series of Step Recovery Diodes.
They are epitaxial silicon varactors which provide high output power and efficiencies in harmonic generator applications.
The SemiGen SRDs offer low snap time through voltages ranging from 8 VDC to 120 VDC, and capacitances ranging from 0.2 pF to 3 pF at 6 VDC.
Below is the Capacitance vs. Bias Curve (@1 MHz) of the MA144769-287 & MAVR-044769-1279 Surface Mount Low Power Step Recovery Diodes (MACOM Technology Solutions Inc.).
This is a basic setup to test SRDs (maybe we'll go into this a little more in a later post):
Now to the Drift Step Recovery Diodes (DSRDs) discovered by Russian scientists in 1981.
The working principle of the DSRD is similar to the SRD but with a substantial difference.
That is, the forward pumping current should be pulsed (not continuous) because drift diodes function with slow carriers.
Keep note at this point that the main phenomenon used in SRDs is the storage of electric charge during forward conduction, which is present in all semiconductor junction diodes and is due to finite lifetime of minority carriers in semiconductors.
To sum up, SRDs are specialized semiconductor devices that come with their own set of advantages (and drawbacks) tailored to specific applications.
And, one of the principal benefits of SRDs is their ability to produce forward current more swiftly than traditional diodes.
It seems that SRDs are discontinued by many suppliers. But fortunately a few manufacturers still produce them for customers servicing legacy radio and microwave systems. So, try it out and have fun!
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