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IWR1443: IWR1443 ADC sample rate and A2D sample rate question, transmitter gain

feng tang
Genius 3595 points
Part Number: IWR1443

The IWR1443 spec says MAX ADC sample rate 37.5 MSPS, A2D MAX sample rate for complex data is 6.25 MSPS

Question 1: Which ADC of IWR1443 have the MAX sample rate of 37.5 MSPS

Question 2:  in "mmWaveEstimator" the "Sampling Frequency Minimum (MSPS)" means "A2D sample rate" or other "ADC sample rate (which ADC)"?

Question 3: Is transmitter gain of IWR1443 adjustable? if yes, what are the transmitter gain range?

Thanks,

  • 0
    TI__Mastermind 37500 points
    Hello,
    There is an Inphase ADC, and a Quadrature ADC in each Rx channel. If you use "real" mode, you only use the Inphase ADC. The ADC has two sample rates depending on the Digital FrontEnd (DFE) output rate. When the DFE output rate is <= 6.25Msps the 900Msps ADC sample rate is selected. The normal ADC sample rate is 1800Msps.

    The Max sample rate is the DFE output rate. The maximum complex (I and Q) DFE output is 18.75Msps. The maximum real (I) DFE output is 37.5Msps.
    The DFE has decimation filters, resamplers, and digital NCOs for the 3 DFE operating modes:
    complex 2x, this is the traditional receiver mode, where we have the ChirpTx - Receiver signal to develop a complex output 0Hz is the center.
    this is used for advanced algorithms, if interference detection is used
    complex 1x, this is the 0 to Fs upper sideband only, this is used for standard range detection, and processing when no negative frequency
    information is used.
    real - this is used for algorithms requiring real (I only processing)

    Answer 1) the Receiver ADCs operate at 900 or 1800Msps. The DFE filters, decimates and mixes the ADC outputs, depending on the desired DFE output mode and rate. The DFE output rate real maximum is 37.5Msps. The DFE output rate complex maximum is 18.75Msps for the IWR1443. The typical range for Complex 1x processing is from 2.5 to 18.75Msps complex.

    Answer 2) the Sampling Frequency Minimum (MSPS) relates to the DFE output rate, when we estimate with the FMCW radar, the Chirp rate, and the 2*distance delay, we develop the maximum beat frequency. Our DFE output rate based on mode needs to be:
    complex 1x - DFE output rate * .9 >= desired beat frequency
    complex 2x or real - DFE output rate * .45 >= desired beat frequency

    Each Transmitter has a 12dbm output. There is a Tx backoff control in db, for each Transmitter. The mmwavelink Profile_Cfg() function controls this.
    there is a 1db per count backoff. I have used the range from -12dbm to 12dbm, ie 24 count range.

    Answer 3) yes, there is an 8bit code, of db_backoff from 12dbm.

    Regards,
    Joe Quintal