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CC1101 Saturation and 1-dB Compression Point

asicman78
Intellectual 895 points

Other Parts Discussed in Thread: CC1101

My customer would like to know how to compare the saturation (-14 to -16dBm) specified in the data sheet to the 1-dB compression point (referred to the input). He says this is the spec he is used to seeing.

Also, since the P1dB is -29dBm a referred to the input, he would like to confirm that he will begin to see overload issues at -39dBm

  • 0
    TI__Mastermind 39860 points

    The IIP3 has not been measured, but simulation results indicate -24 dBm. The 1 dB compression point is 10 dB below IIP3, i.e. -34 dBm

    The saturation limit is not set by the LNA+mixer, but by the ADC. CC1101 includes a programmable attenuation stage between mixer and ADC. See register FIFOTHR.CLOSE_IN_RX. Adding a 3 dB attenuation improves saturation level by 3 dB, but also degrades sensitivity by 3 dB.

  • 0 in reply to Sverre
    Intellectual 895 points
    Thanks for the information. My customer is comparing the CC1101 to a rival ADI transceiver. The ADI transceiver specifies saturation as +10dBm while the CC1101 provides a range of -14 to -17 dBm, comparing these too numbers solely on the values is probably incorrect, how is saturation defined for the CC1101? Can it be compared as a function/relation to P1dB?
  • 0 in reply to asicman78
    TI__Mastermind 39860 points

    Saturation limit is the maximum input power you can have at the antenna and still have packet error rate less than 1%. DN010 explains how to increse the saturation limit through register FIFOTHR. See TI web.

    Note that saturation limit is only important if the TX and RX parts are close. Assuming +10 dBm output power and 915 MHz operation, the two units need to less than approx 1 meter apart for saturation to be an issue. If the units are closer than this you can lower the output power on the TX side (and save current) or improve saturation level as outlined in DN010.