Question about AD8370

Hi All,

Comparing Fig 47 with Fig 52 depicted in AD8370 data sheet, what are major differences? Both outputs (OPHI and OPLO) are biased to midsupply (Vocm). In what case, AD8138 should be used?

My spec is 10MHz single-end input --> AD8370_50dB amplify --> AD9215BRUZ_100MHz sampling.

Best Regards,

Kazu

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  • Hi, Kazu,

        The AD8370 runs on single 5V supply, so the input and output common-mode range are ~ +/- 1.6V around mid-supply (i.e., from 0.9 to 4.1V), but max. output swing will be reduced as the output common-mode level approaches either extreme.  The AD8138, running on dual supply, can extend the output common-mode range to include 0V and negative voltage levels.  The AD8138 will not be necessary when the AD8370 interfaces to the AD9215 ADC, as the latter supports a wide common-mode input range (0.5 - 2.5V, see Fig. 31 on AD9215 datasheet) that overlaps with the AD8370's.  E.g., both parts will operate well with a common-mode level set to 2.0 V.

    Benjamin

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