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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 Naveen,

         Sorry that this difficulty remains.  I had confused the SSM2166 with the differential-input pre-amp ICs often used where I work, but actually the SSM2166's data sheet shows it has a single-ended input.  Thus the MIC-Low input is the same as ground, and only one LC filter is needed as shown below.  This schematic is simply that of the chip's evaluation board, to which I added the LC filter.  I show it as a pseudo-differential input in case you wish to use a three-pin mic with the usual "balanced" (2 conductors plus shield) cable -- however in this case you would be better off with a true differential preamp (or an input transformer, but those get expensive)..

         I'm wondering how strong, and how close, is the FM transmitter involved.  Also whether the preamp circuit is in a shield box.  I also show in red a 220 pF cap you could try adding directly across the op-amp inputs.

        

         Best regards,

         Bob

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  •     Hello Naveen,

         Sorry that this difficulty remains.  I had confused the SSM2166 with the differential-input pre-amp ICs often used where I work, but actually the SSM2166's data sheet shows it has a single-ended input.  Thus the MIC-Low input is the same as ground, and only one LC filter is needed as shown below.  This schematic is simply that of the chip's evaluation board, to which I added the LC filter.  I show it as a pseudo-differential input in case you wish to use a three-pin mic with the usual "balanced" (2 conductors plus shield) cable -- however in this case you would be better off with a true differential preamp (or an input transformer, but those get expensive)..

         I'm wondering how strong, and how close, is the FM transmitter involved.  Also whether the preamp circuit is in a shield box.  I also show in red a 220 pF cap you could try adding directly across the op-amp inputs.

        

         Best regards,

         Bob

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