How is differential input full-scale defined?

Jason Work

Other Parts Discussed in Thread: ADC3421

How is differential input full-scale defined for the ADC3421?

Given these specifications:

Differential input full-scale voltage: 2 Vpp
Input common-mode voltage: 0.95 V

Then does this mean that the input pins INAP and INAM can be any voltage within the range of 0.45 V to 1.45 V, but nothing outside of this range?

over 9 years ago

0 Ken C over 9 years ago

TI__Genius 12965 points

Jason,
That is correct. Each pin can swing +/-0.5V around the common mode voltage of 0.95V to produce a differential 2Vpp max input signal. Typically going beyond these compliance ranges will result in degraded performance.
Ken.

0 Jason Work over 9 years ago in reply to Ken C

TI__Genius 10830 points

Yes, thanks for clarifying. This agrees with the datasheet.

Reference:

ADC3421 datasheet
Find, “must swing”

I see also that input range should be half of that for input frequencies up to 600 MHz (450 MHz or higher).

Reference:

ADC3421 datasheet
Find, “Differential input voltage”

0 Ken C over 9 years ago in reply to Jason Work

TI__Genius 12965 points

Yes - that is also correct. For the highest frequencies the recommendation is to drive the input with a lower voltage.
Ken.

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How is differential input full-scale defined?