I am planning to amplify AC signal (without sacrificing dynamic range) using MCP602(Microchip), but the datasheet shows input voltage is from 2.7V to 6.0V. My question is can I use negative supply in the MCP602, instead of ground. Do dual supply op-amps are different from signal supply op-ams, or can we use both interchangeably.

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Yes, but the difference between the positive and negative supply voltages must be between 2.7 and 6V.

You can also AC couple the input and use divider resistors to generate a voltage mid-way between V+ and V- without using a split supply.


simulate this circuit – Schematic created using CircuitLab

You could also use a resistor divider to generate Vcc/2 and connect the ground side of the AC input signal to that instead of using the AC coupling capacitor and R1-R2 divider.

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  • \$\begingroup\$ In the schematic show, the dynamic rang of the input signal would suffer, as we can amplify the signal till Vcc/2. My question is can we use dual supply in single supply op-amp. \$\endgroup\$ – TapasX Oct 27 '17 at 8:50
  • \$\begingroup\$ Every op amp is a dual supply one. However a single supply op amp often means it will work close to or right up to the negative rail so you can connect the negative supply to ground in a circuit. The opamp can't tell the difference between ground and negative- it will just see a different input common mode voltage. \$\endgroup\$ – Joren Vaes Oct 27 '17 at 13:04
  • \$\begingroup\$ The circuit does not affect dynamic range vs split supplies. Either way, for the MSP1602, the linear output range is Vss + 100mV to Vdd - 100mV. So, if you are using a 6V single ended power supply, your output can swing from 100mV (0V + 100mV) to 5.9V (6V - 100mV) for a total swing of 5.8V. If you use a split supply of -3V and 3V, your output swing ends up -2.9V to 2.9V for a total swing of 5.8V. As others have said, there is no difference between a single ended or split supply opamp except the techniques for ground referencing the input. \$\endgroup\$ – Dean Franks Oct 27 '17 at 18:30

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