Hey All,
I've been pulling my hair out all weekend trying to figure this one out. I am having trouble connecting two phases of an multi op-amp circuit together.
I'm trying to take a small differential signal (~10mV), amplify it, and then fullwave rectify it using only single supply opamp configurations. To do this I'm taking advantage of the differential amplifiers reference pin and giving it +Vs/2. This causes the output to have a DC offset wrt to GND (0V) [V1 below]. I then pass it through a HPF to remove this offset before sending it to the fullwave rectifier [V2 below]. See the attached image.
I've got both phases working independently. The differential amplifier and the HPF output the correct waveform when not connected to the fullwave rectifier portion of the circuit [everything after V2] and the fullwave rectifier will take a waveform similar to V2 and output a wave form similar to Vout.
However, when I connect the output of the HPF to the input of the fullwave rectifier circuit, the signal at V2 gains a DC offset close but not exactly back to where it was at V1!
What can cause this?!
(The differential amplifier is AD8226 and the gen purpose opamp (rectifier phase) is a LM6134. Both opamps are using the same +Vs and GND planes.)
Thanks for your time,
Brian
I've been pulling my hair out all weekend trying to figure this one out. I am having trouble connecting two phases of an multi op-amp circuit together.
I'm trying to take a small differential signal (~10mV), amplify it, and then fullwave rectify it using only single supply opamp configurations. To do this I'm taking advantage of the differential amplifiers reference pin and giving it +Vs/2. This causes the output to have a DC offset wrt to GND (0V) [V1 below]. I then pass it through a HPF to remove this offset before sending it to the fullwave rectifier [V2 below]. See the attached image.
I've got both phases working independently. The differential amplifier and the HPF output the correct waveform when not connected to the fullwave rectifier portion of the circuit [everything after V2] and the fullwave rectifier will take a waveform similar to V2 and output a wave form similar to Vout.
However, when I connect the output of the HPF to the input of the fullwave rectifier circuit, the signal at V2 gains a DC offset close but not exactly back to where it was at V1!
What can cause this?!
(The differential amplifier is AD8226 and the gen purpose opamp (rectifier phase) is a LM6134. Both opamps are using the same +Vs and GND planes.)
Thanks for your time,
Brian