0
\$\begingroup\$

Also, how is there a theoretical/practical upper limit to slew rates? Suppose a customer wanted an extreme high speed op amp with a slew rate of, say, 5 Volts per femtosecond(which would translate to 5GV/μs)? Would that even be possible with a purely electronic op amp or would optics be required.

\$\endgroup\$
7
  • 1
    \$\begingroup\$ An odd question. What do you need it for? Or is it homework? Perhaps the highest available slew rates costs a hundred thousand dollars, is it still useful for you? \$\endgroup\$
    – user253751
    Jan 31, 2020 at 17:18
  • 2
    \$\begingroup\$ Let me consult the Guinness Book of Analog Electronics and get back to you. \$\endgroup\$
    – user16324
    Jan 31, 2020 at 17:29
  • \$\begingroup\$ How would optics generate a rapid voltage change? \$\endgroup\$ Jan 31, 2020 at 17:36
  • \$\begingroup\$ 500MHz is the max I have seen. What current do you expect into 1pF at this rate, then you can determine the source impedance or current per picofarad. Ic=CdV/dt = 1e-12*5e9 * 1e6 = 60e3 Amps 60 thousand amps into 1 picofarad. How about an EMP? Sorry no negative feedback MR X. For EO parts they are not Op AMPs but GaAs semiconductors. \$\endgroup\$ Jan 31, 2020 at 17:44
  • \$\begingroup\$ There are 6.5 GHz fully-differential amps like the LMH5401 or ADL5569 with up to 24 kV/µs. \$\endgroup\$
    – CL.
    Jan 31, 2020 at 18:21

1 Answer 1

3
\$\begingroup\$

It's kind of an odd question. According to Digikey the fastest opamp slew rate is currently 24V/ns. ADL5569

But keep in mind the context - opamps are intended to have well-controlled, low-noise, linear outputs. This means that their slew rates are always "held back" to allow for good stability.

If you use digital circuits, like fast logic gates, the maximum slew rate is far higher. For example, I have worked with digital logic that has a slew rate of about 100V/ns.

Ultimately, the slew rate will be limited by the RLC characteristics of your circuit. And that is totally dependent on what you are trying to use the circuit for.

\$\endgroup\$

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