microphoneoperational-amplifiervoltage-clipping
I have the following circuit and I want to process the output of the op-amp through an ADC. However, as you can see in the picture the signal is clipping at 1.89 Volts, rather than 3Volts. Why is it doing that? Does it have to do with the biasing of the amplifier?? The signal I applied was a 19 kHz sine wave.
Circuit diagram:
Output capture:
Check this out from the datasheet:
If your feedback resistor is much less than about 1K with +/-15V supplies, it's going to oscillate like a banshee with only a tiny amount of load capacitance (such as a scope probe).
First, thank you for the well-written question.
Based on your scope captures, I suspect the mid-rail biasing is not working correctly. You should be able to check the output bias voltage by shorting Vo1 and IN- together, then measuring the voltage at Vo1. (Turn your input sine wave off first, obviously.) You should see about 1.6V. If it's more like 0.8V, check R3 and R6. You should also verify that your electrolytic capacitors are connected the right way.
Best Answer
You might need to look for rail to Rail op-amps if the output of op-amp is expected to be close to supply voltage.
Below spec is from datasheet of LM358 op-amp which tells that the difference can be upto 1.5 V from the VCC (3 V, in OP case)
Suggestion:
MCP6001 from Microchip. Datasheet here