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CC1200 - Saturation, blocking and SAW filter question

Enrico Migliore
Intellectual 690 points
Other Parts Discussed in Thread: CC1200

Hi,

I'm designing a board with the CC1200 transceiver and I need to pass the R&TTE and EMC tests.

MY OPINION:

The CC1200 transceiver has a very high level of saturation (10 dBm) but that doesn't prevent from blocking.

10 dBm is very good when no interfering signals are present.

Out-of-band interfering (blocking) signals greater than -40 dBm can still prevent the reception from being correct.

QUESTION 1:

Very high level of saturation doesn't prevent from blocking when interfering signals are present.

Do you agree?

QUESTION 2:

Why do you state in the datasheet that the saw filter is not needed?

Thank you in advance,

Enrico Migliore

  • 0
    TI__Guru**** 317180 points
    Q1: A saturation level of +10 dBm ensure that the chip will not be damaged in the present of high field strengths. What do you base your statement of -40 dBm interferer on? We have run a lot of blocking tests where the interferer is higher (without SAW) and still error free communication.

    Q2: CC1200 is compliant with the standards stated in the datasheet without using a SAW filter.
  • 0 in reply to TER
    Intellectual 690 points
    Dear TER,

    thank you for your answer.

    > What do you base your statement of -40 dBm interferer on?
    As far as I know, blocking is the difference between the sensitivity of the receiver (-122 dBm @ 12.5 KHz channel, 1.2 kbps , 2-FSK) and the power of the interfering signal.

    We have 82 dB blocking @ 10 MHz spacing. That means that a -40 dBm signal can still create interference.

    Am I right?


    Thank you,
    Enrico Migliore
  • 0 in reply to Enrico Migliore
    TI__Guru**** 317180 points

    Pr ETSI blocking is defined as the difference between the signal (3 dB above sensitivity limit) and the blocker. Then the blocker in your case is at -120 +82 = -38 dBm but if your signal is at -110 dBm the blocker could be up to -28 dBm and so on.