• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 21 subscribers
  • Views 848 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMX2492: Change Pump out and vtune range

Sthefany Alvarez
Prodigy 20 points
Part Number: LMX2492

We adquired LMX2492 chip in order to enhance performance in a continuous wave radar using the ramp generation. We are using a VCO that requires Vtune range 3 V to 12 V to work from 500 MHz to 1000 MHz.

In the LMX2492 datasheet  just specifies that the current max of the CPout 3.1 mA and the CPout voltage is 2.5 V ( Vcp = 5V in my case).

I expect to generate a triangle signal using LMX2492 and connect to this VCO to work in a frequency range 500 MHz - 1000 MHz.

I would like to integrate this VCO to the LMX2492. So, I don't figure out how to make sure the VCO vtune is properly generating and the changes I have to do to the loop filter.

Any suggestions and advice will be welcomed.

Thank you for your attention.

Sthefany

  • 0
    TI__Expert 8335 points
    Hi Sthefany,

    Yes the CPout voltage is up to 2.5V normally. And the opamp serves the function of going above that. If you see in our EVM user's guide, the board has option to put a 5V opamp (by default not populated). You can follow that as an example for your use case.

    Regards,

    Brian Wang
  • 0 in reply to Brian Wang
    Prodigy 20 points

    Thank you Mr. Brian for your reply.

    I figured out that in the EVM user guide just mentioned it but there is not explain for other opamps. I was using active filter type C in simulation to achieve tuning voltage 3V- 12V

    I also try to generate a triangle signal (using ramp feature) with 1 us period.  Dou you kindly suggest the loop bandwidth needed in order to accomplish this ? I am simulating using PLLatium Sim and it gives me a loop bandwidth 4MHz  for a lock time  0.8 us (Fosc=fpd= 10 MHz)

    Thank you.