The amplifier input impedance with negative feedback can be calculated using the formula:
Zin(f) = Zin / (1 + Aβ)
where β is the feedback fraction, which is equal to rf / (rf + ri).
Substituting the given values, we get:
β = rf / (rf + ri) = 47kΩ / (47kΩ + 1.0kΩ) = 0.979
Zin(f) = 1MΩ / (1 + 200,000 * 0.979) = 5.11 kΩ
Therefore, the amplifier input impedance with negative feedback is 5.11 kΩ.
Noninverting Amplifier, the op-amp parameters are given as follows:
A = 200,000, Zin = 1MΩ and Zout=100Ω.
Calculate the amplifier input impedance (with negative feedback).
rf =47kΩ
ri = 1.0kΩ
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