AD8422: Trouble on Power Supply affects In-Amp Performance

Hello everybody,

I have a question regarding the Power Supply of the Instrumentation Amplifier AD8422. I’d like to power the device with

+-12 V generated by a DC/DC-Converter. Due to the DC/DC conversion the power supply contains Voltage peaks with a frequency of 300 kHz (Figure 2). As a result of the disturbance on the power supply the DC Input Voltage (approx. 700 mV) of the In-Amp, which should be amplified with a Factor of 10, has the same disturbance patterns on its output (Figure 3). So my question is: Is it normal that this kind of disturbances has this severe effect on the output voltage of the amplifier?

Description of the Schematic:

The goal of the schematic in Figure 1 is to amplify the Input Voltage, which is proportional to Temperature and has a range of 500 mV to 700 mV, by a Factor of 10. I’d like to achieve accuracy of U < 100 µV on the output. The input Signal is differential and has a maximum frequency of approx. 25 kHz. The source of the input Voltage is a low-impedance one.

Thank you for your help!

Florian

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    •  Analog Employees 
    on Aug 2, 2018 3:26 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin
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  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:26 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin
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