I've built a non-inverting buffer using an MCP6002 powered from 5V.
I'm feeding a ramp voltage as Vin
I'm measuring Vin and Vout with an ADS1115 16 bit ADC
I'm puzzled as to how I can be getting a gain of >1 when I expect Avcl = Avol/1+Avol

 

Hi Whistler,
Welcome to AAC.
Please post your circuit diagram.
What are your voltage source impedances.?
E

 

Input Offset-Voltage and Current.
.
.
.

 

If it is a simple gain of one follower configuration with the output directly connected to the minus input, then the anomaly is possibly due to the input offset voltage and the common-mode error of the op amp.
Also a rail-rail op amp operating from 0V to the supply voltage can have additional small offset errors at the extremes of the signal.

You are seeing very small deviations from the ideal.

 

Input offsetvoltage und -current.

The ADS1115 will also add some error to your messurement. It has gain channel match of 0.05 to 0.1% and an offset channel match of 3LSB. This can also contribute to your gainerror.

 

Thanks for prompt replies!



https://ww1.microchip.com/downloads...1U-2-4-1-MHz-Low-Power-Op-Amp-DS20001733L.pdf

Ibias & Ioffset are pA; Vos 5mV

Input offsetvoltage und -current.

The ADS1115 will also add some error to your messurement. It has gain channel match of 0.05 to 0.1% and an offset channel match of 3LSB. This can also contribute to your gainerror.