CC1350 dualband RF path

pixbroker

Other Parts Discussed in Thread: CC1350, CC1190, CC2650

I know there is not much disclosed about the CC1350 just yet (can't wait, so excited). But meanwhile we have a general question about the RF path for a dual band device like this? will there be 2 pairs of balanced RF pins one for each band or will the 2 bands share one balanced pair? if they share, will there be some external switcher required?

we are looking at CC1350 for an upcoming design and were just wondering about the general path implications for a dual band device like that.

thanks.

over 8 years ago

0 Fredrik K over 8 years ago

TI__Guru** 106705 points

Hi Pixbroker,

The pinout of the CC13xx will be the same as for CC26xx, it will in other words have one differential RF output. The simplest way to use this in dual band systems is to use each RF pin as single ended output and use one for 2.4 GHz and one for sub-1 GHz. You can also use external switches, but that will make the design quite complex.

Note that questions about the CC13xx should be placed in the Proprietary Sub 1 GHz forum: e2e.ti.com/.../156

Cheers,
Fredrik

0 pixbroker over 8 years ago in reply to Fredrik K

Genius 5820 points

Thank you for your prompt response. That sounds great. Didn't think about that but the CC26xx data sheet already provides some indication. I assume you are talking about something like this:

Feel free to move this thread to the Sub 1GHz section of the forum.

Thanks,

-r

0 Fredrik K over 8 years ago in reply to pixbroker

TI__Guru** 106705 points

Yes, something like that.

0 CHS over 8 years ago in reply to pixbroker

TI__Mastermind 18780 points

Moved the thread to the appropriate forum.

The solution you draw above is correct, however component values and configuration for single-ended operation for the different frequency bands are to my knowledge not ready yet (and will off course not be the same for the different bands. There are also other differential solutions for dual band operations that are possible, but they will have switches and a higher component count.

0 pixbroker over 8 years ago in reply to CHS

Genius 5820 points

Thanks CHS,

sure, i just crabbed the single ended 2 antenna drawing from the CC26xx data sheet.

Is it known yet which of the 2 pins will be for the Sub 1GHz band and which one for BLE? P or N?

Also, if CC1350 will be used with CC1190 for Sub 1GHz range extender, will there be support to drive the PA_EN and LNA_EN pins of the CC1190 from dedicated GPIO pins for automatic TX/RX switching?

Thanks.

-r

0 Fredrik K over 8 years ago in reply to pixbroker

TI__Guru** 106705 points

Hi R,

You can select RF pins freely.

Control signals for CC1190/CC259x is described in the Technical Reference Manual chapter 11.3.2.1.

Cheers,
Fredrik

0 pixbroker over 8 years ago in reply to Fredrik K

Genius 5820 points

Fredrik K said:

Control signals for CC1190/CC259x is described in the Technical Reference Manual chapter 11.3.2.1.

where can one find the "Technical Reference Manual" for CC1350?

0 Sverre over 8 years ago in reply to pixbroker

TI__Mastermind 39860 points

Use the CC26xx TRM: http://www.ti.com//lit/swcu117.

There The same document will also be a the CC13xx TRM when we officially release the part in August.

0 pixbroker over 8 years ago in reply to Sverre

Genius 5820 points

Thanks!

Re the "freely assignable RF pins", this is unique to the CC13xx? as i cannot see this feature in CC26xx TRM.

0 Fredrik K over 8 years ago in reply to pixbroker

TI__Guru** 106705 points

From the TRM: "The signals can be mapped to any DIO by setting the relevant PORTID in the designated [IOCFGx] register." I am not sure how this is unclear.

This was obviously not what you asked about.

When I said you can freely assign the RF pins, I meant that 2.4 GHz and sub-1 GHz output is not locked to RF_P or RF_N. You can choose yourself which RF pin to use for which frequency.

Cheers,
Fredrik

0 Sverre over 8 years ago in reply to pixbroker

TI__Mastermind 39860 points

Noticed Fredrik's answer, but I think you mean the RF pins.....

You can either have 1 differential path, or 1 single ended path (approx 1 dB degradation in sensitivity, 3 dB degradation in output power compared to differential mode), or 2 single ended paths (e.g one at 433 MHz, one at 868 MHz or even one at sub-1 and the other at 2.4 GHz when using CC1350). The configuration is set through overrides. Do not have the bit fields in my head but do a search for ".frontEndMode"

0 pixbroker over 8 years ago in reply to Fredrik K

Genius 5820 points

Ok, thanks for the clarification, i was starting to 2nd guess my question :)

Ok, so just to be clear, the 2 RF pins are fixed, but the frequencies can be assigned to either of them.

Thanks!

0 Fredrik K over 8 years ago in reply to pixbroker

TI__Guru** 106705 points

Exactly. I updated my post when I realized I had misinterpreted your question.

0 pixbroker over 8 years ago in reply to Sverre

Genius 5820 points

Sverre said:

approx 1 dB degradation in sensitivity, 3 dB degradation in output power compared to differential mode)

So in order to get best performance, one would have to go with 1 differential path and use an external switch?

0 Fredrik K over 8 years ago in reply to pixbroker

TI__Guru** 106705 points

Yes, at the cost of a (much) more complex design. There will be reference designs for both options.

0 Fredrik K over 8 years ago in reply to pixbroker

TI__Guru** 106705 points

I did not see your block diagram when I wrote the last reply. You cannot use the same balun for both frequency bands, so you must place the switches infront of the balun(s).

0 pixbroker over 8 years ago in reply to Fredrik K

Genius 5820 points

Fredrik K said:

you must place the switches infront of the balun(s).

Oh, of course, i updated the diagram for correctness.

thanks.

0 pixbroker over 8 years ago in reply to pixbroker

Genius 5820 points

The CC2650 has 2 RF pins. RF_N and RF_P. For CC1350, can you elaborate which one of these will be for 900MHz and which one will be for BLE if both bands will be used in a single ended configuration? or is each band freely assignable to either of the 2 pins?

0 Fredrik K over 8 years ago in reply to pixbroker

TI__Guru** 106705 points

Each pin is freely assignable to either band.

0 pixbroker over 8 years ago in reply to Fredrik K

Genius 5820 points

thank you.

Sub-1 GHz

Sub-1 GHz forum

CC1350 dualband RF path