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Combining two DACs for enhanced resolution

Masaharu Katayama
Expert 1420 points

Hi

May I ask how much resolution will be improved by combining two DAC in below devices?

2 x DAC3154 (10 bit)

2 x DAC3164 (12 bit)

2 x DAC3174 (14 bit)

If two 10 bit DACs will make 16bit, like DAC5681 it will be great. But not likely using open loop, just adding two DAC outputs with OPA.  I wonder if I can trade off INL/DNL between composite low resolution(better linearlity) DAC and single high resolution DAC.

Best regards,

Masa

  • 0
    TI__Mastermind 29220 points

    Hi,

    Combining two DACs in parallel for current summing would in theory lead to better resolution - *if* the device-to-device gain mismatches and clock skews could be calibrated out.  But in practice the device to device mismatch in clock propageation would be an issue and precisely controlling the relative gain between two separate devices would make the proposition be not really feasible.

    Regards,

    Richard P.

  • 0 in reply to Richard Prentice
    Expert 1420 points

    Hi Richard,

    Thank you very much for your technical advice. I understand that this way may not be recommended. However I would like to get your thought if the following reluxing may work.

    1) Application allows 100ns setteling time. A typical propagation delay of the DACs is 2ns which is 2% of the settling time.  

    2) Calibrate initial offset and gain

    3) Use high grade external voltage reference (temperature drift 2-3ppm/C).

    if 2-4 bits can be enhanced, it would be great. May I get your thought if it has a chance?

    Best regards,

    Masa