# AD8131 Single Ended to Differential Problem

I am attempting to convert a single ended signal (0-5V) to a differential signal (+/- 5V about 0V) using an AD8131ARZ. I have it wired as per the attached schematic. When I supply +5V to the positive input DIN+ of the AD8131, the output behaves correctly with +/- 5V. However, if I ground the DIN+ input the outputs hold at or near 0V instead of inverting. So, it halfway works.

Experimenting, if I disconnect DIN- from ground and apply a voltage slightly more positive than zero to it while grounding DIN+ I begin to get the desired effect of the signals inverting. However, the amplitude is not correct. The amplitude appears to be the difference only (gain of 1).

How can I achieve my stated goal with this IC?

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• You cannot apply 5V Vin to this amplifier, it has Gain=2, and only +-5V supplies. To convert 0-5V to differential, you need something with much higher power rails, +-15V or somethiing. Jan 14, 2017 at 17:16
• What happens if you disconnect DIN- from GND? Jan 14, 2017 at 17:30

$25°C, V_S = ±5 V, V_{OCM} = 0 V, G = 2, R_{L, dm} = 200 Ω$

Input Common-Mode Voltage = −1.0 to +4.0 V

Output Voltage Swing Maximum ΔV OUT ; single-ended output 1.0 to 3.7 V

These are the specs. Read carefully.