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1k~100kHz sine wave generator & detector

zhenhua lin5
Prodigy 70 points
Other Parts Discussed in Thread: DAC8532, PCM5100A, DAC8811

hi all，

I need to produce a sine wave with the frequency of  1k to 100kHZ， and amplitude of  1mV~100mV，  can you give a a recommendation IC for that ， thanks, Can I use DAC8532 for that.

and i also need to test the sine wave 's peak value of root square value， is it possible to measure it with a normal  AD converter？ or it needs some peripheral circuits ， please give me some advise 

thank you  

  • 0
    TI__Genius 14220 points
    Hi Zhenhua,

    Thank you for your query. I am looking into your problem. I will get back by next week.

    Regards,
    Uttam Sahu
    Applications Engineer, Precision DACs
  • 0 in reply to Uttam Sahu
    TI__Guru 52673 points
    Hi Zhenhua,

    There are a few ways that you could implement this.
    1. You could use an audio DAC with a higher sample rate - for example you could use the PCM5100A with a sample rate of 200kHz.
    2. You could use one of our MDACs such as the DAC8811. MDACs offer fast settling time, but will need to be buffered externally if you are going to drive any kind of load with the output. You could use a low voltage reference, but I would not recommend it. I think you should use a higher reference, then attenuate the output to the 100mV range with an external opamp.

    Finally how you could measure the RMS voltage is not a simple questions. If you know that the input signal is a sinewave, and will always be a sinewave, then you can use an ADC with a fast sample rate. If you are expecting 100kHz to be the high frequency you will measure, then you would want an ADC that will be able to measure the Vpeak value of the sinewave no matter the phase of the signal, think >500ksps. Then all you need to do is measure the peak value of the input wave. Vrms= Vpeak/sqrt(2) for a sign wave. If you are trying to measure the RMS value of a arbitrary wave form, then you will need to implement some kind of TRUERMS measurement method, and that a bit out of scope of this forum questions.

    Thanks!
    Paul
  • 0 in reply to Paul_Frost
    Prodigy 70 points
    Hi Paul，
    thank you for your reply.
    but there is still a question，the settling time of DAC8811 is 0.5us, does it mean it can create a variable value at 1/0.5us=2000000Hz，and if I choose 20 points for a sine wave，I can have a 100kHz one? if I want to get a more precise sine wave， I need to choose a faster settling time.
    thank you
  • 0 in reply to zhenhua lin5
    TI__Guru 52673 points
    Hi Zhenhua,

    Yes, you should be able to..

    Thanks,
    Paul