LMX2595: Frequency sweep time question

JAEHOON KIM

Part Number: LMX2595

hello.

We want to control the 12.17GHz to 12.235GHz range with LMX2595 in 0.5MHz Step. (Control mode or Ramping mode)
(ex: 1: 12.170GHz -> 2: 12.1705GHz, 3: 12.171GHz ... )

Can I know the time it takes to control with 0.5MHz Step?
(I wonder if the control time between steps is within 10us.)

The MCU used is FPGA (XC7K70T-1FBG484I).

over 2 years ago

+1 Noel Fung over 2 years ago

TI__Guru** 114760 points

Hi Kim,

You can use Manual Ramp mode with a 100kHz RampClk, output frequency will change every 10us.

+1 vicente flores prado over 2 years ago

TI__Mastermind 31542 points

Hi Jaehoon,

Due to instruments, I was only able to take plot of 1MHz step. But nevertheless under 10us. Thus, a 0.5MHz step under 10us should be no issue.

Regards,

Vicenten

0 JAEHOON KIM over 2 years ago in reply to vicente flores prado

Intellectual 565 points

The input frequency I use is 48MHz, not 100MHz.
Still, isn't it the same whether the frequency can be changed within 10us?

0 vicente flores prado over 2 years ago in reply to JAEHOON KIM

TI__Mastermind 31542 points

Hi Jaehoon,
Yes that shouldn't be an issue - step size should still be within 10us.

Regards,

Vicente

0 JAEHOON KIM over 2 years ago in reply to vicente flores prado

Intellectual 565 points

I have additional questions.

Is it possible to control the PLL frequency within 10us in 0.5MHz steps according to a specific signal (external signal)? (For example, every time 0.5MHz steps are controlled, a signal comes from the outside, and the PLL frequency must be changed to match the signal. The change time is within 10us.)

Regards,

KIM

0 vicente flores prado over 2 years ago in reply to JAEHOON KIM

TI__Mastermind 31542 points

Hi Kim,
LMX2595 IS controllable via SPI - thus external signal from MCU can program the VCO frequency to different values but LMX2595 itself does not have a native way to be controlled by changing OSCIN for example and expecting the VCO frequency to change automatically assuming I understood your question correctly.

Regards,

Vicente

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LMX2595: Frequency sweep time question