AD630 lock in amp application for DC signal

Q 

In AD630 DS, it says AD630 can be used to build up a lock-in amp to pick up
narrow band signal from big noise. I would like to know if the lock-in amp can
work with DC signal, if a low level DC signal buried in the noise, can we use
lock-in amp to pick up it.

 

A 

The AD630 operates synchronously, referring a signal with high noise content to
a known frequency reference. Therefore the dc case would be irrelevant. One can
simply filter noise from dc to detect any dc level present.
Comments
Anonymous
    •  Analog Employees 
    in reply to cjg

    Hi cjg,

    Please ask your question in the Amplifier forum and someone will answer you.

    Thanks!

  • Hello,

    I want to use the AD630 in my application. Like the original poster, I am wondering about DC signals. I have an optical sensor that outputs a modulated signal (a constant square wave of 2kHz, no carrier (since it has no data)), due to LEDs turning on and off at 2kHz. Is it in my case also totally unnecessary to use a lock-in amplifier? I mean, I have a square wave signal that varies between 0V and +400mV that I would like to isolate from noise with much higher amplitude. It's not AC in that it doesn't have dual polarities, but it's not a constant DC signal either. If lock-in is unnecessary and if there are simpler ways for my application, could you please advice me on such? Thanks in advance.

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