1. An op-amp is connected in the noninverting amplifier configuration. A voltage source
of value $v_s$ is connected via a series resistance $R_s$ to the $v_+$ terminal.
a) Find an expression for $V_{OUT}$ as a function of $v_s$ if the op-amp is ideal.
b) If the op-amp is nonideal and has input bias currents $I_+$ and $I_-$ and input offset
voltage $V_{IO}$, find an expression for $V_{OUT}$ when $v_s$=0.
c) Combine the answers to parts (a) and (b) to find the total output when $v_s$ is
nonzero.
d) The feedback resistors in the amplifier are set to 25k$\Omega$ and 100 k$\Omega$, so that the
amplifier has a gain of 5. If $I_{BIAS}=(I_++I_-)/2$=100 nA, $I_{IO}$=-40nA, and $V_{IO}$=2mV,
what value of $R_s$ will minimize the total dc offset component to $V_{OUT}$?
a)
$V_{out} = v_s \left(\frac{R_f + R_i}{R_i}\right)$
b)
$V_{out} = V_{IO} \left(\frac{R_f + R_i}{R_i}\right) - I_+ R_s \left(\frac{R_f + R_i}{R_i}\right)$
$+ I_- R_f$
