Let’s look at the reason we need to design the buffer. If we direct connect the sensor to adc input –
We will have 1V * 1k/(100k + 1k) ~= 10mV only, clearly this is not acceptable. Note that in Mindi, instead of using R1, R2 ... you can right click on component and change its name, in this case Radc is the name chosen to represent the ADC.
To simulate – all spice required “Ground” symbol for reference, so let’s insert one as below, double click on V1 and rename it to Vsensor, and change name of R1 to Rout.
We want to know the voltage at ADC input, so place voltage marker on the interconnect node for Rout, Radc to see the voltage
Schematic after placing marker:
Then choose simulation mode to be DCOP
And click “Run”
Now you see the need for buffer circuit. DCOP is the first thing that I recommend for any simulation, since it let you see the DC biasing in the schematic itself – especially when the circuit is much more complicated than this. You can place as many markers as required.