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THS3092: Designing a DAC output smoothing amplifier.

Yash Jasnani
Prodigy 30 points
Part Number: THS3092


Dear Experts,

I need your experties to design a DAC output smoothing amplifier.

I am using DAC Evaluation board DC2459A with LT1668, at 10MHz to 20MHz CLK and the Signal will be of 1MHz to 7MHz. I get stair case waveform at the output of DAC. So need a smoothing circuit at output stage. Further I will be driving piezo.

I have tried few circuits designs. In Circuit 1 I get 1MHz smooth waveform but than it starts attenuating as I go higher. I figured out that by decreasing C3 (100n) starting point of attenuation shifted to 2MHz,3MHz, and so on but the waveform is not smooth as with 100n.

In Circuit 2 I have added LPF at before Rin(R1) whose cutoff frequency is 12MHz but here at just 1MHz staircase is been observed at the output of the op amplifier.

  • 0
    TI__Expert 6050 points

    Hi,

    Can you provide more information on the output signal of the DAC that you are inputting to the amplifier? You show the DAC output as an AC voltage of +/- 1V. According to the datasheet of the LTC1668, distortion can occur when using amplitudes in that range.

    Are the behaviors you are describing for circuits 1 and 2 observed from simulation or measured? It may help to provide the simulation files you are using. 

    One thing that may improve the performance is increasing the sampling frequency, as well. 

    Thanks,

    Nick