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ADC12D1800, 12-bit, single 3.6 GSPS high-speed ADC

dana spinuzzi
Prodigy 10 points

on page 15 of the specification (table 4.3 recommended operating conditions) the maximum Vin +/- voltage range is 2.4V (DC coupled input). The stated Vin +/- differential voltage range is also stated as 2.0V (DC coupled at 20% duty cycle). Lastly, the Vin+/- power is stated as +15.3 dBm (AC coupled mode) and +17.1 dBm (AC coupled mode not maintaining common mode voltage).

Can you please explain why the differences between DC coupled (2.4V = +11.5 dBm) and (1.0V = +10 dBm) (DC coupled at 100% duty)? I'm making the assumption that the voltages in table 4.3 are peak-to-peak voltages in a 50 ohm system. Does the "DC coupled" mode imply 100% duty factor of the input waveform?


Also, can you explain the distinction between the power levels (15.3 and 17.1 dBm) for AC coupled modes (i.e. not maintaining versus maintaining common mode voltage) what does this mean? Thank you.

  • 0
    TI__Mastermind 20541 points

    Hi Dana,

    We are looking into this will reply as soon as we can.

    Regards,

    Neeraj Gill

  • 0 in reply to Neeraj Gill
    TI__Mastermind 20541 points

    Hi Dana,

    VIN +/- Voltage range of -0.4V to 2.4V is the minimum and maximum absolute voltage that can be applied to VIN +/- PINS.

    VIN +/- Voltage is Differential voltage range of 1.0V (DC-coupled at 100% duty cycle) means a differential voltage of 1V can be applied between VIN + and Vin - without degrading the performance of the ADC. AND 2.0V at 20% duty cycle means the voltage difference between VIN+ and VIN- is 2V only 20% of the time for the input signal. Similarly a voltage difference of 2.8V between VIN+ and VIN- pins for 10% of time for input signal will not degrade the performance of the ADC.

    For the VIN +/- Power parameter 15.3dBm is maximum input signal power if your common mode voltage is 1.35V and 17.1 dBm is max signal power when you common mode voltage is 1.15V.

    Regards,

    Neeraj Gill