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Single ended to differential mic signal driver recommendations

Thread Summary

The user seeks recommendations for single-ended to unity-gain differential signal drivers for microphone signals with low output impedance, noise, and quiescent current (<5mA). The final answer suggests that the user's application might require a higher input level for the ADC, and recommends checking the AD1938 datasheet for a relevant circuit. The engineer also advises exploring the linear amplifiers section of the forum for more specific solutions and searching for similar questions.
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Category: Hardware
Product Number: e.g. LTC6363, LT6350

Anyone have recommendations for single ended to unity-gain differential signal drivers for microphone signals at low output impedance, noise, and quiescent current (<5mA)? I see some chips like LTC6363-1 and LT6350 but these indicate SAR optimization. My application would interface with a downstream ADC/preamp which I presume falls into sigma-delta category. Would these types of chips by an issue? Looking for compact solution that eliminates delays, cascading noise, etc. Thanks in advance for any input.

Edit Notes

clarified ADC interface type
[edited by: Kapila at 7:16 PM (GMT -4) on 17 May 2023]
  • Hello Kapila,

    You kind of are describing two different applications. An ADC will usually require an input level that is higher than a mic level signal. Although it does depend on what the AVDD voltage the part is operating on. Our newer parts that run on 1.8V require a small signal as a full-scale input. 

    I captured this circuit from the AD1938 datasheet. It is an older design and you will probably not like the way it inverts. 

    It is meant to drive an ADC with a 3.3V power rail that is sitting up at around a 1.5V common mode voltage. This is a very common circuit and can be a good starting point. 

    Even though this is a good audio question, you are probably better to ask this on the linear amplifiers section of the forum. (+) Amplifiers - EngineerZone (analog.com)

    I think they should be able to help and also try searching that forum space for answers.

    Dave T

  • Hi Dave, thanks for the input. I'll be sure to check out your suggestions.