Brief of Application:
The signal conditioning circuit developed is used to detect or capture the peak values of dynamic systems such as the impulse tools. In this application, we use an impulse tool to tighten or loosen bolts and nuts, hence when the torque is applied to tighten or loosen the bolts at a set torque, my system should detect the peak torque applied to tightening the screws.
The Figure above shows the schematic of the circuit developed in Multisim i.e. An Instrumentation Amplifier followed by a Peak Detector.
Description of the Problem
The output across the capacitor goes as input to the TI-ADC1790. The problem is, the output at the peak detector has a small negative offset of -4.7 mV because of which some ADC counts are lost for the initial readings, since the ADC starts counting from the positive voltage scale. Hence, while testing I noticed that, when I apply the torque, the values are acquired only from the start of the positive scale. Therefore I need to compensate the negative offset to the ADC input.
Two ways I feel this can be done is by using an adder circuit at the output to switch the peak detector output to a positive scale or just use a voltage follower circuit while providing certain gain to amplifying the negative offset to a positive scale.
I am posting this question here, expecting to get a more appropriate solutions to this. Therefore, any help, suggestions or advice regarding this would be great. Thank you.