# Is it possible to amplify AC signal with In Amp in Single Supply?

Is it possible to amplify AC signal with In Amp in Single Supply, however, with a sufficient reference to 'compensate' the negative part of the signal?

I believe that a in amp with a single supply, for example 5V and GND, can not amplify negative signals because the power is not symmetrical. Right? Or not?

My point is:

If I add a reference (Pin 5) that makes the signal completely positive, is it possible to amplify this signal? Having as a result a fully positive amplified signal?

I'm using a in amp (INA118) with single supply (GND on pin 4 and 5V on pin 7) with gain equal to 2 (Rg = 50KOhm). On reference pin 5 I'm adding + 2.5V (Vdd / 2).

In my project, I need to inject a 1mA electric current into the patient's body through 2 electrodes, receive this signal through 2 other electrodes, and amplify this signal. Like This. The sine is a sinusoid of 1.98V pp and 1mA (With a frequency sweep from 1KHz to 100KHz) with the voltage ranging from -0.99V to +0.99V. The Schematic is like this.

• Can you string the complete diagram together, please: current source,.. patient,.. InAmp?.. Reference electrode, perhaps?.. You are not leaving that to us, are you? Feb 17 '17 at 0:28
• Nick, The Schematic is like this: i.stack.imgur.com/PU6cr.png I will use o AD5933 and a HPF (High pass filter or Capacitor Block DC), in the output of the HPF, the voltage will be 1.98V pp (-0.99V to +0.99V). The current source use two opamps (AD8606 with single supply +5V), the outputs of the current source (E1, E2) are the 2 current eletrodes, Z represent the patient's body, and E3, E4 are the two voltage electrodes. The AD5933 is a Sine wave generator and a ADC. Feb 17 '17 at 1:22