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CC1020: Harmonics reduction in transceiver

Part Number: CC1020
Other Parts Discussed in Thread: CC1311R3, CC1101, CC110L

Tool/software:

Hi,

      I am using CC1020 as a transceiver for 433MHz UHF range. While operating it in Tx mode with +8dBm, the 2nd harmonic power level is too high i.e., -15dBc rather than specified -50dBc in datasheet. With reduction in output power say +1dBm the harmonic level is reduced to -30dBc.

  • Why the harmonic level is increasing with increase in output power ?
  • Why the harmonic level is not fixed at -30dBc for higher output power ?
  • What are the causes & how to reduce harmonics level ?
  • Hi,

    In order to step through this please can you provide the following initial information:

    • Is this test using custom hardware or a TI EVM?
    • What is your measurement setup (presumably these are conducted measurements)? Are you using SmartRF Studio 7 to configure the device?
    • What are your RF settings?

    Regards,

    Zack

  • Hi,

    The details of test are as follows:

    • Test is made using custom hardware in conducted mode.
    • Register values are taken from Smart RF Studio 6 & given as mentioned below
    • Freq 2A- 39
    • Freq 1A- F0
    • Freq 0A- 0F
    • CLK_A- 3A
    • Freq 2B- 39
    • Freq 1B- FA
    • Freq 0B- B9
    • CLK_B- 3A
  • Hi,

    Please can you describe your measurement setup in more detail?

    Regards,

    Zack

  • Hi,

    •  We are using one board with CC1020 as transmitter & another board with CC1020 as receiver.
    • We have made one external PA module for transmitter for 2 Watt & 5 watt power levels.
    • We found that the harmonic level in transceiver itself is higher than specified -50dBc for 433 MHz.
    • The PA power level in reg value is 58 & value observed in spectrum is +1.0dBm.
    • Measurement setup sequence is: DC Power Supply, Transceiver board, RF cable(1.0dB loss), Spectrum Analyzer.
    • Power supply voltage to transceiver is : +3.28V
  • When you state:

    We found that the harmonic level in transceiver itself is higher than specified -50dBc for 433 MHz.

    Can you share the spectrum analyser screenshot for this? Are you soldering a semi-rigid cable after the transceiver's balun/filtering network (or something else)?

    Regards,
    Zack

  • Hello,

     Please find the attached spectrum images for three different PA power levels:

    Low Power: PA Reg - 01h Output power: -26 dBm

    Medium Power: PA Reg - 58h Output power: +1.3 dBm

    High Power: PA Reg - FFh Output power: +8.0 dBm

    Note that the custom board has SMA jack which is through hole PCB mount & later there is a RF cable connected to Spectrum Analyzer with insertion loss of 0.15 dB @433 MHz

  • Hi,

    Thank you for the plots. Assuming this is the CC1020 alone (not combined with the external PA), which is what I understand from your replies, that is a very high 2nd harmonic for ~8 dBm output power.

    It is worth looking at your HW design - please can you submit it using Sub-1 GHz Design Review Submission: https://www.ti.com/tool/SIMPLELINK-SUB1GHZ-DESIGN-REVIEWS

    We would recommend switching to a newer device such as the CC1101 or CC110L transceivers, or the CC1311R3 SoC - this would make it easier to support and you will get better RF performance using these devices.

    Regards,

    Zack

  • Hi,

    I can confirm that we've received the design review. I will mark this thread as "Resolved" as we will send the completed review via email.

    Regards,

    Zack