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ADAU1701 Lock-in amplifier

Hi,
I would like to design a "Lock-in amplifier" using ADAU1701 DSP chip. Lock-in uses a technique known as phase sensitive detection to single out the component of the signal at a specific frequency. Signals at other frequencies are rejected through software (DSP lock-in) filtering.  Would it be possible to design a lock-in amplifier using ADAU170?
I was thinking to use ADAU1701 DSP chip, with SigmaStudio graphical development tool in order to design Lock-in amplifier as shown in the figure. I added noise, to the input signal of interest(500Hz), the reference signal is also 500 Hz, two multipliers have been used as mixers for IQ demodulation(after multiplication of signals, we should get DC(0Hz) signal and 1000Hz signal because its output will be two signals with f1-f2 and f1+f2 frequencies), Hilbert transform was used to the output signal and its 90 phase shifted version. After demodulation, it goes through the filter in order to filter out 2f frequency and etc.
I was thinking to buy EVAL-ADAU1701MINIZ, together with USBi control interface board. If there is a better alternative, I would be glad to know.
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  • Hi Beste,

    Looking at your scopeshot, it looks like perhaps Tone 1 and Tone 2 are not perfectly synchronized - but that could be a subtlety under the hood of SigmaStudio, best asked in the sigmadsp forum.

    Can you repost the question there, and I'd also recommend adding some detail on your circuit setup. Is this a single board, or are the Tone 1 and Tone 2 generators on two separate boards?

    -Mark