Sampling diodes: Difference between revisions
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The original diodes are no longer available. When sampling diodes need replacement, there are two options. They can be scavenged from other | The original diodes are no longer available. When sampling diodes need replacement, there are two options. They can be scavenged from other | ||
gear or replacements can be improvised using modern parts. [[Hewlett-Packard|HP/Avago]] and now Broadcom makes integrated pairs and quads of high-speed Schottky diodes (e.g. HSMS-28xx series). These are a decent replacement for the original diodes. | gear or replacements can be improvised using modern parts. [[Hewlett-Packard|HP/Avago]] and now Broadcom makes integrated pairs and quads of high-speed Schottky diodes (e.g. HSMS-28xx series). These are a decent replacement for the original diodes. | ||
== recommend diode as substitute == | |||
{| class="wikitable" | |||
|- | |||
! Type of Diode | |||
! Unit | |||
! reached risetime | |||
! note | |||
|- | |||
| HSMS2822 || [[4S1]] || 320 ps || meeting specification | |||
|- | |||
| HSMS2822 || [[S-2]] || 120 ps || don't reached specification | |||
|- | |||
| MMDL301 || [[S-2]] || 185 ps || much blowby, not recommend | |||
|- | |||
|} | |||
<gallery> | <gallery> | ||
Revision as of 11:25, 28 January 2019
There are at least two kinds of sampling diodes used in classic Tek sampling gear, GaAs junction diodes and Schottky diodes. It is easy for these diodes to get destroyed by ESD. They are designed to have low capacitance, which means that a small amount of charge can produce a potentially damaging voltage across the diode.
If the output of a sampler has a large DC shift even with no input to the sampler (an external triggering), and does not respond to the DC offset control, it is possible that one or more sampling diodes could be damaged.
The original diodes are no longer available. When sampling diodes need replacement, there are two options. They can be scavenged from other gear or replacements can be improvised using modern parts. HP/Avago and now Broadcom makes integrated pairs and quads of high-speed Schottky diodes (e.g. HSMS-28xx series). These are a decent replacement for the original diodes.
recommend diode as substitute
| Type of Diode | Unit | reached risetime | note |
|---|---|---|---|
| HSMS2822 | 4S1 | 320 ps | meeting specification |
| HSMS2822 | S-2 | 120 ps | don't reached specification |
| MMDL301 | S-2 | 185 ps | much blowby, not recommend |
-
4S1 Sampling diode replacing by Avago HSMS2822 Diode.
