Tx interpolation filter THB0/THBO

According to UG-992 Figure 80, page 166,there is a THBO in the Tx signal path (strangely with letter 'O', instead of digit '0'), but I found no other reference of it.

How can it be configured?

Is it related to the <txInputHbInterpolation=1> from the Filter Wizard?

What about the API? I guess: txInputHbInterpolation;     /*!< Interpolation of half band filter before the programmable FIR (valid 1,2,4) */

But in the code generated by the TES, the comment is slightly different: /* TxInputHbInterpolation (1,2)*/

Thank you

  • 0
    •  Analog Employees 
    on Aug 6, 2019 6:27 AM

    This is somehow missed in our UG-992 document. Thanks for pointing this out. We will add this info to UG-992 in next revision.

    THB0 (AD9375 only)

    The Transmit Half Band 0 (THB0) is a fixed coefficient half band interpolating filter. The THB0 is only available in the AD9375 product variants of the Mykonos family. The THB0 can interpolate by a factor of 2 or it can be bypassed. The full-scale value of this filter is 32768 (215).

    THB0 Filter Coefficients: [33, 0, -159, 0, 493, 0, -1216, 0, 2677, 0, -5944, 0, 20503, 32768, 20503, 0, -5944, 0, 2677, 0, -1216, 0, 492, 0, -159, 0, 33]

  • Has there been any updates to this? The filter wizard nor TES  takes advantage of this either. Is there an MYKONOS structure for this or API?

  • 0
    •  Analog Employees 
    on Apr 19, 2021 11:10 AM in reply to Jpayne

    Are you using AD9375 device? What is the profile you are using?

    If you are using AD9375, To enable the THB0 for AD9375, "2, /* TxInputHbInterpolation (1,2)*/" has to be set to 2 manually and  to enbale DPD "1 /* Enable DPD, only valid for AD9373*/" has to be set to 1 manually.

    For example,

    static mykonosTxProfile_t txProfile =
    { /* TxDPD 40/200MHz, IQrate 122.88MSPS, Dec5 */
    DACDIV_2p5, /* The divider used to generate the DAC clock*/
    &txFir, /* Pointer to Tx FIR filter structure*/
    1, /* The Tx digital FIR filter interpolation (1,2,4)*/
    2, /* Tx Halfband1 filter interpolation (1,2)*/
    1, /* Tx Halfband2 filter interpolation (1,2)*/
    2, /* TxInputHbInterpolation (1,2)*/
    122880, /* Tx IQ data rate in kHz*/
    60000000, /* Primary Signal BW*/
    200000000, /* The Tx RF passband bandwidth for the profile*/
    189477, /* The DAC filter 3dB corner in kHz*/
    100000, /* Tx BBF 3dB corner in kHz*/
    1 /* Enable DPD, only valid for AD9373*/
    };