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AWR1243: Local oscillator phase and gain mismatch between receive channels

Jonathan Jones2
Intellectual 680 points
Part Number: AWR1243

Dear TI support,

Please can you let me know what the Local Oscillator phase and gain mismatch is between the four receive channels is on the AWR1243.

So this the maximum difference in phase and amplitude between the Local Oscillator (LO) signals for any two of the four receivers.

Also, in the AWR1243 datasheet it gives IQ phase mismatch (2deg) and gain mismatch (1dB): Could you clarify if this is mismatch between I and Q signals for one receive path?

I appreciate your help with this.

Yours faithfully,

Jonathan

  • 0
    TI__Mastermind 22155 points
    Hello Jonathan,
    We will get back to you on this ASAP.

    Thanks,
    Raghu
  • 0
    TI__Prodigy 545 points

    Hi Jonathan,

    The raw phase mismatch of the channels cannot be directly measured because it is not possible to separate out the variations of the phase errors on the board and the chip.  The variation of the phase mismatch over temperature is less than 3 degrees.  Similarly, the variation over temperature of the gain mismatch is less than 1dB.

    The IQ gain and phase mismatch are the specifications of the mismatch between I and Q within a single receive path.

    Regards,

    Brian

  • 0 in reply to bginzz
    Intellectual 680 points
    Hi Brian,

    I appreciate your quick response on this issue.

    So for a given temperature should we assume that there is no significant LO phase difference between the four receive channels and that the main phase difference at between the receive channels will be due to differences in track lengths to the receive antennas?

    Regarding the receiver gain mismatch variation of <1dB and phase mismatch variation <3deg over temperature: is this the variation of the gain and phase mismatch of the entire receive path?

    Could you also confirm the temperature range over which you the <1dB, <3deg mismatch variation is seen? Is this Tj = -40degC to +125degC?

    Best regards

    Jonathan
  • 0 in reply to Jonathan Jones2
    TI__Prodigy 545 points
    Hi Jonathan,

    We find that even nominally length matched traces on the same PCB can have significant (>10 degrees) phase mismatch. This means that we cannot isolate the chip phase difference; therefore, there may be LO phase difference between the four RX channels, and for high accuracy angle measurements, the combined board + chip phase mismatch would have to be compensated. The stability of the chip's RX phase mismatch over temperature means that this calibration should be possible at only a single temperature.

    The reported values of the gain and phase mismatch are for the entire RX path. In measurements, we can't practically separate out the RF and LO path mismatches.

    You are correct. The temperature range for the <1dB, <3deg mismatch variation is for a junction temperature from Tj=-40degJ to +125degC.

    Regards,
    Brian
  • 0 in reply to bginzz
    Intellectual 680 points
    Hi Brian.

    Thank you for your reply.
    That is very clear.

    Best regards

    Jonathan