6
\$\begingroup\$

Why don't they use zener diodes in high frequencies?

\$\endgroup\$
8
\$\begingroup\$

In reverse biased mode, which is how you would normally use a zener, the capacitance is tens to hundreds of picofarads. This could be enough to attenuate your signal significantly, depending on the frequency and source impedance.

\$\endgroup\$
  • \$\begingroup\$ The large-ish capacitance of a Zener is one of the reasons they need alternative architectures for ESD protection on very high-speed data lines. \$\endgroup\$ – ajs410 Apr 20 '11 at 16:48
  • \$\begingroup\$ @Martin- Is there a relationship mobility of holes in PN junction? \$\endgroup\$ – Cell-o Apr 21 '11 at 20:55
  • \$\begingroup\$ @Cell-o, you'll have to look that up. As a practising engineer, I haven't had the need to use zeners with anything approaching RF so the theoretical reason for the capacitance isn't something that springs to mind. \$\endgroup\$ – Martin Apr 22 '11 at 15:08
3
\$\begingroup\$

Zener diodes aren't typically used in a signal path. You won't find them easily in lower frequency paths either. They're used mostly to control DC voltages.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.