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LM7171: Unipolar Supply VCC

Brian Wang0928
Genius 15130 points

Part Number: LM7171

Is this LM7171 able to use unipolar supply VCC (V- pin is connected to ground)?

Regards,

Brian

  • 0
    Guru 140200 points
    Hi Brian,

    yes, this is possible, provided your supply voltage is above +10V and you don't violate the common mode input voltage range. Take care, with the LM7171 the input voltage must stay 1.8V away from the rails. So, only the input voltage range between 1.8V and 8.2V is allowed with a supply voltage of 10V.

    Powering an HF OPAmp with only a single supply voltage has several disadvantages. When setting the DC operating point, voltage dividers connected between the rails are usually used. These voltage dividers can heavily increase the supply current. And they can inject supply noise directly into the current path! So, additionally filtering might be needed which can considerably increase the component count. Also, to provide AC coupling huge capacitances might be needed in the high pass filters. In very high frequency OPAmp circuits the inductance of these huge caps can make trouble, so that these caps must be paralleled by smaller capacitances, which additionally increases the component count.

    Kai