0
\$\begingroup\$

I am currently using an FPGA (Virtex II NI RIO7831R) to generate the clock for a pulse generator used to drive a Linbo3 optical phase modulator. http://www.jdsu.com/en-us/Optical-Communications/Products/a-z-product-list/Pages/modulator-ape-phase.aspx#.VXmz-0YpoiI

I would like to directly use the fpga to drive the modulator in real time but i need to generate up to 10 volt square wave with rising time less than 5/10 ns.

Does someone has an idea how to generate a square wave with such a fast rise time?

Than you in advance

\$\endgroup\$
1
  • 1
    \$\begingroup\$ There are chips available specifically for this purpose. They are called "modulator drivers". However they are typically much faster than 5-10 ns rise/fall time (10 to 40 GHz are more usual specs). Unfortunately your spec is in a bit of a bad spot. Probably too fast for an op-amp solution, too slow to justify buying an expensive driver chip. \$\endgroup\$
    – The Photon
    Jun 11 '15 at 16:59
1
\$\begingroup\$

While I may have misunderstood your drive requirements, a MOSFET gate driver would seem to be a good place to start. TI makes a line http://www.ti.com/lsds/ti/power-management/gate-driver-products.page#p9=3.2;5.3&p528=4;6&p529=12;14&p248=1;7.6&p598=TTL and a UCC27611 seems a decent choice. 5 nsec rise and fall times, and 10 volts into 50 ohms is .2 amps, while the IC will do .3 amps average. It comes in a very small package, too. And lots of other manufacturers make something similar, so I'm not specifically recommending this one, just using it as an example.

\$\endgroup\$
0
\$\begingroup\$

Depending on how much current the modulator requires, one solution might be a current feedback op amp. There are a number of high slew rate op amps with slew rates just about where you want it. One possible part is the LME49713. It's a current feedback op amp with 132 MHz of bandwidth and 1900 V/us slew rate. It should be possible to get a 10V swing in 10 ns out of that thing.

\$\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.