SPIRTI1 + SKY66100-11 power consumption

[mauro]

Posted on April 28, 2015 at 11:13

Hi,

I'm testing a solution with Spirit1 + SKY66100-11 for 169MHz transmission.

I have a 600mA current consumption with spirit1+sky 66100-11+TCXO. Is it normal?

Where Can I found a detailed technical report of current consumption ?

Thanks for the help.

#sky66100-11 #spirit1 #169mhz

[pecorino.salvatore-giorgio]

Posted on May 05, 2015 at 10:14

Hi,

Our reference design STEVAL-IKR002V7D (http://www.st.com/web/en/catalog/tools/PF259552) has a current consumption of about 350 mA @ 27 dBm with 3.3V.

Are You using our reference design or your own solution with similar BOM? What is the supply voltage provided to the RF board? And what is the measured RF output power?

Thank You

S

[mauro]

Posted on May 12, 2015 at 17:57

Dear Pecorino,

thanks for the support.

I use a very similar design to the reference.

Main voltage is 3V6.

I think that I find the problem. It's the uncorrect antenna matching.

I tried with a better antenna and the power consumption decreased.

Can I ask you another question?

What is the best setting of the output power from the spirit1? Is it -6dBm for to have +27dBm at the PA output?

Best regards

[pecorino.salvatore-giorgio]

Posted on May 13, 2015 at 10:48

Hello,

Yes, you are right about the fact a current consumption problem can be related to a mismatch of the application board.

About the RF output power setting to achieve the +27 dBm, the better choice is to select the lowest output power setting of the SPIRIT1.

Due to the fact that this can change according to the application board (layout, BOM) the best way is measuring the RF output power and find out the right setting increasing the SPIRIT1 power until the target is fulfilled.

Best Regards,

S

[nicolas239955]

Posted on June 20, 2015 at 12:25

Hello everyone,

I have the same problem on a board I developed.

I observed that when board is connected to the spectrum analyser, consumption of the PA is fine.

When I connect it to the eval kit antenna, consumption of the Skyworks is multiplied by something like 1.5

If I put a 20dB attenuator between board and antenna, consumption is fine again.

I wonder whether it is related to radiated emi... What do you think?

Whatever happens, it becomes hard to make measurements because of radiated emi. Scope probes receive the 169Mhz signal... Damn Schrodinger!!

[nicolas239955]

Posted on June 20, 2015 at 13:27

Dear all,

After reading a bit more about antenna theory here is what I think:

The eval kit antenna is a monopole antenna. It is not mounted on any ground plane. Could this lead to an impedance mismatch large enough that PAE of the PA drops, thus leading to the observed additive consumption?

Mauro, you said everything was back to normal after changing the antenna... What antennas did you used? Which types?

Thanks again,

Nicolas