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i am looking for suitable replacement for SSM2166 (mic preamp)...pls suggest the best solution

In our applications we have observed that SSM2166 is vulnerable/susceptible to Radio Emissions (with AM modulation) from near by VHF system. In order to overcome this pls suggest the alternative for SSM2166.....

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  •      Hello,

         I don't see an ADI drop-in replacement for the SSM2166, however I've experienced mic preamp RFI susceptibility & have found it best to use RF filtering ahead of the chip.  Series 47 uH inductors in each input line with shunt 0.01 uF caps to ground work well.  This combination resonates at about 230 KHz, sufficiently below the AM broadcast band.  Be careful not to allow your filter to resonate within broadcast frequencies or else you may end up with a radio receiver instead of a mic preamp.

         All differential amplifiers have sensitive input transistors with junctions that can rectify / detect RF energy.  Keeping RF away from them definitely helps.

         Best regards,

         Bob

Reply
  •      Hello,

         I don't see an ADI drop-in replacement for the SSM2166, however I've experienced mic preamp RFI susceptibility & have found it best to use RF filtering ahead of the chip.  Series 47 uH inductors in each input line with shunt 0.01 uF caps to ground work well.  This combination resonates at about 230 KHz, sufficiently below the AM broadcast band.  Be careful not to allow your filter to resonate within broadcast frequencies or else you may end up with a radio receiver instead of a mic preamp.

         All differential amplifiers have sensitive input transistors with junctions that can rectify / detect RF energy.  Keeping RF away from them definitely helps.

         Best regards,

         Bob

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