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LMX2694-SEP: Output power control function

Part Number: LMX2694-SEP
Other Parts Discussed in Thread: LMX2594

Dear Team,

Please kindly look into the below question, thank you for your guidance.

We are optimizing the feedback power control algorithm of our LMX2694 synthesizers.

At the moment we are using a simple proportional control, where the PLL power register is adjusted via SPI to maintain a constant output power vs temperature and vs frequency at the mixer input.

 

We want to improve it by importing the measured output power transfer characteristic, in order to have faster convergence and less overshoot, without doing complex analysis.

 

I saw that the LMX2694 datasheet doesn't show any figure regarding this.

But I saw that the figure is available on the LMX2594 datasheet (Figure 20), but:

- for resistor pull-up only

- at 8 GHz only

 

Therefore my questions are:

- is the same Figure applicable for LMX2694?

- is the same Figure/curve applicable for inductor pull-up? (since it's normalized)

- does the normalized curve shift vs frequency?

  • Hi Daniel,

    We will see similar power code vs output power plot as Figure 20. This is because the same power control mechanism is applied in LMX2694. 

    Inductor pull-up also has similar characteristic except that output power is higher. 

    Only the output power will shift with frequency, the characteristic of power code vs output power remains similar.