Step Recovery Diode Applications
- the step recovery diode finds applications in a number of areas including harmonic generation and multipliers as well as in pulse shaper circuits.
The step recovery diode, SRD finds a number of applications in circuits including harmonic generation or harmonic multipliers and also for pulse shaping.
Although not widely used these days, the SRD can still be used in a number of applications where other approaches may not be as suitable.
Step recovery diode multiplier
Step recovery diodes are used, even today as high order multipliers. As a result of their speed and overall operation they are able to multiply the frequency of signals by as much as 20x when used as a comb generator.
The diodes use their extremely fast recovery time, often referred to as "snap time" to generate pulses from an original signal that are very rich in harmonics.
Proper filtering and pulse shaping produces the familiar output of sharp, fast rise time pulses.
The diode operates by storing charge during the positive half of an input sinusoidal signal. This charge is then used during the negative going half cycle. It provides a current pulse with a rise time equivalent to the 'snap time' of the diode to the impulse circuit of the multiplier. Filters in the output of the overall circuit are then used to select the required harmonic.
As multipliers, step recovery diodes can have cut-off frequencies of 200 to 300 GHz. This makes them more than adequate to be used as the key device in multipliers operating at frequencies up to 10 GHz and more.
As a multiplier, these diodes can have very high levels of efficiency. The maximum level of efficiency achievable can be approximated to 1 / n where n is the multiplication ratio, and it approximately holds for multiplication levels greater than about 3.
For low order multipliers high efficiency levels can be achieved. Often as high as 65% for doublers and 50% for triplers.
By Ian Poole
Read more about semiconductor diodes . . . . .
|• Diode types||• PN junction||• Diode specifications||• Gunn diode|
|• IMPATT diode||• Laser diode||• Photo diode||• PIN diode|
|• Schottky diode||• Step recovery diode||• Tunnel diode||• Varactor diode|
|• Zener diode||• Light emitting diode||• BARITT diode||• Backward diode|
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