Question

QUESTION 49 The circuit shown has Rp = 70 K2 and R1 = 5 k. The following values are obtained from the op-amp's data sheet: Aol = 20,000, Zin = 1.5 M2 and Zout = 1502. Determine the input impedance of the circuit. Via + V. ov, 축 0010 000 0 200 0 75 me 0 3060 050

Answer 1

The formulae of input impedance of non inverting amplifier is

$Z_{I}=Z_{in}(1+\frac{A_{OL}R_{I}}{R_{I}+R_{F}})$

$Z_{I}=1.5*10^{6}(1+\frac{20000*5}{5+70})$

$Z_{I}=1.5*10^{6}(1+\frac{20000*5}{75})$

$Z_{I}=1.5*10^{6}(1+\frac{20000}{15})$

$Z_{I}=1.5*10^{6}(1+1333.33)$

$Z_{I}=1.5*10^{6}*1334.33$

$Z_{I}=2001.495*10^{6}$

$Z_{I}=2*10^{9}\Omega$

$Z_{I}=2G\Omega$