Some fancy function generators have a burst feature which gives precise control over on-time and periodicity of the desired waveform.

Ex: For my application, I have a 25 MHz sin wave (2.5 Vpp) and, in the burst settings, I could set the following:

  • Number of cycles = 10 cyc
    • This would mean that my on-time would be only 5*(1/25e6) = 400 ns
  • Burst period = 50 us
    • For my application, the period must be greater than or equal to 50 us.

However my function generator, which is actually just an oscilloscope (Rigol DS1104Z+) with 2 programmable sources, does not have this burst feature. I tried to find some workaround by looking through the source related commands in the programming guide (pages 125–136) to no avail. The closest I got was using the built in amplitude modulator with a square wave envelope but there is no way to control the duty cycle.

If there is no programmatic way to obtain this functionality, is there an easy (and cheap) way to do this with simple external hardware?

  • 1
    \$\begingroup\$ I see it has an "amplitude modulation" feature, can you use that with a square wave modulating a sine wave between 0% and 100% levels? \$\endgroup\$ – bobflux Mar 13 at 8:07
  • \$\begingroup\$ @bobflux you’re talking about the modulation depth? It is already set to 100%. The problem is that its duty cycle is statically set at 50% so it is useless to me. \$\endgroup\$ – Landon Mar 14 at 7:54
  • \$\begingroup\$ Ah, ok. I thought it could AM with one channel as carrier and the other as modulation, but no, it has another special snowflake generator just for AM that doesn't know how to do a duty cycle. Bummer. You could use a channel set to pulse driving a RF switch or analog switch that switches on/off the channel set to sine... \$\endgroup\$ – bobflux Mar 14 at 9:51
  • \$\begingroup\$ @bobflux Ya I thought about that too but the only switch I could find that is fast enough (<2 us release time) is the MM5600 MEMS relay by Menlo Micro which won’t hit the market until later this year.. \$\endgroup\$ – Landon Mar 14 at 9:57
  • \$\begingroup\$ There are analog FET switches that switch in nanoseconds (use a SPDT switch so output is either input or shorted to ground). But you'll always get some leakage... \$\endgroup\$ – bobflux Mar 14 at 12:41

Your Answer

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

Browse other questions tagged or ask your own question.