the circuit diagram：
the result of oscilloscope (The voltage between Vout+ and GND):
Any insight would be appreciated.
Please set your common-mode voltage near the midsupply (2.5V) to maximize the output swing. Refer to figure 10 to 13 of the AD8421 datasheet for more details on this and also to this video about input common-mode voltage vs. output voltage.
Also, set your input voltage between 2.3V and 3.2V because you're using single supply of 5V.
thank you for your answer，
But I've added the REF pin a voltage（2.5V） by op184，Is this not a right way？
how should I set？
figure 10 to 13 of the AD8421 datasheet only given Relationship between common-mode voltage and output voltage under situation of dual power supply ，Do you have the data when it is under singal power supply？
thank you so much
The problem is resolved With your help ，thank you so much
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