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:

Circuit diagram

Output capture: enter image description here


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)

enter image description here


MCP6001 from Microchip. Datasheet here

enter image description here

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  • \$\begingroup\$ Looking at the schematic of the LM358 (page 13 of TI's datasheet) then I see that the ouput stage has an NPN darlington arrangement for pulling the output high. This can never pull the output higher than Vcc - 1.4 V or thereabouts, just as mentioned in this answer. Solution: use a CMOS based opamp like the MPC6001 or TLC271. The LM358 works with a supply of 3V but it's more suited to higher supply voltages. \$\endgroup\$ – Bimpelrekkie Jul 7 '15 at 8:09

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