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lab05_en:inverting_op-amp_basics_amplification [2026/04/02 11:34] – [Investigation of inverting input] mexleadminlab05_en:inverting_op-amp_basics_amplification [2026/04/28 16:21] (current) – [Analysis of inverting input currents] mexleadmin
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 $U_{\rm IN}{\rm~=}$ $U_{\rm IN}{\rm~=}$
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-== Investigation of inverting input ==+== Analysis of inverting input currents ==
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 {{drawio>lab05:Fig-30_inverting_op-amp_inv_input.svg}} {{drawio>lab05:Fig-30_inverting_op-amp_inv_input.svg}}
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-<imgcaption Fig-30_inverting_op-amp_inv_input | Inverting Op-Amp: Investigate currents of the inverting input> </imgcaption>+<imgcaption Fig-30_inverting_op-amp_inv_input | Inverting Op-Amp: Analysis of currents of the inverting input> </imgcaption>
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 $U_{\rm DD}{\rm~=10~V},~U_{\rm SS}{\rm~=-10~V},~R_{\rm 1}{\rm~=10~k\Omega}$\\ \\ $U_{\rm DD}{\rm~=10~V},~U_{\rm SS}{\rm~=-10~V},~R_{\rm 1}{\rm~=10~k\Omega}$\\ \\
 Use the values from <imgref Fig-20_inverting_op-amp> for $U_{\rm IN},~U_{\rm OUT},~R_{\rm 2}$. Use the values from <imgref Fig-20_inverting_op-amp> for $U_{\rm IN},~U_{\rm OUT},~R_{\rm 2}$.
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 Complete the arrows in the scematic of the circuit.\\ Complete the arrows in the scematic of the circuit.\\
-Determine the the currents $I_{\rm 1}$ and $I_{\rm 2}$ indirectly through a voltage measurement.\\ +Determine the the currents $I_{\rm 1}$ and $I_{\rm 2}$ indirectly by measuring the voltage across known resistors\\ 
-Calculate the sum of the currents at node ${\rm N_{12}}$. +and calculate the algebraic sum of the currents at node $N_{\rm {12}}$ using Kirchhoff’s Current Law (KCL).
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-$U_{\rm 2}{\rm~=}$+$U_{\rm 2}{\rm~=}$\\
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-$I_{\rm 1}{\rm~=}$ 
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-$I_{\rm 2}{\rm~=}$ 
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-$I_{\rm N12}{\rm~=}$ 
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-{{drawio>lab05:Fig-40_inverting_op-amp_inv_input_virt_gnd.svg}} 
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-<imgcaption Fig-40_inverting_op-amp_inv_input_virt_gnd | Inverting Op-Amp: Investigate the virtual GND of the inverting input> </imgcaption> 
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-$U_{\rm DD}{\rm~=10~V},~U_{\rm SS}{\rm~=-10~V},~R_{\rm 1}{\rm~=10~k\Omega}$\\ \\ 
-Use the values from <imgref Fig-20_inverting_op-amp> for $U_{\rm IN},~U_{\rm OUT},~R_{\rm 2}$. 
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 +$I_{\rm 1}{\rm~=}$
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-Complete the arrows in the scematic of the circuit.\\ 
-Determine the the currents $I_{\rm 1}$ and $I_{\rm 2}$ indirectly through a voltage measurement.\\ 
-Calculate the sum of the currents at node ${\rm N_{12}}$. 
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 +$I_{\rm 2}{\rm~=}$
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-$U_{\rm 1}{\rm~=}$ 
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 +$I_{\rm N12}{\rm~=}$
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-$U_{\rm 2}{\rm~=}$ 
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 +== Analysis of inverting input voltages ==
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 +{{drawio>lab05:Fig-40_inverting_op-amp_inv_input_virt_gnd.svg}}
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 +<imgcaption Fig-40_inverting_op-amp_inv_input_virt_gnd | Inverting Op-Amp: Analysis of virtual GND of the inverting input> </imgcaption>
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 +$U_{\rm DD}{\rm~=10~V},~U_{\rm SS}{\rm~=-10~V},~R_{\rm 1}{\rm~=10~k\Omega}$\\ \\
 +Use the values from <imgref Fig-20_inverting_op-amp> for $U_{\rm IN},~U_{\rm OUT},~R_{\rm 2}$.
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 +Complete the reference arrows in the scematic of the circuit.\\
 +Take the values for $U_{\rm 1},~U_{\rm 2},~U_{\rm OUT}$ from <imgref Fig-30_inverting_op-amp_inv_input>.\\
 +Calculate the voltage $U_{12}$ using Kirchhoff's Voltage Law (KVL) within the circuit loop.\\
 +Verify your calculated result by measuring $U_{12}$.
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 +$U_{\rm 1}{\rm~=}$
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 +$U_{\rm 2}{\rm~=}$
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 +$U_{\rm OUT}{\rm~=}$
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 +Calculated $U_{\rm 12}{\rm~=}$
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 +Measured $U_{\rm 12}{\rm~=}$
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 +Analyse the physical significance of the potential at $N_{12}$ relative to GND (defined as $U_{12}$) in the context of the operational amplifier's input configuration. What do you observe?\\
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 +${\rm ................................................................................................}$ \\ \\
 +${\rm ................................................................................................}$ \\ \\
 +${\rm ................................................................................................}$ \\ \\
 +${\rm ................................................................................................}$ \\ \\
 +${\rm ................................................................................................}$ \\ \\
 +${\rm ................................................................................................}$ \\ \\
 +${\rm ................................................................................................}$ \\ \\
 +${\rm ................................................................................................}$ \\ \\
 +${\rm ................................................................................................}$ \\ \\
 +${\rm ................................................................................................}$ \\ \\
 +${\rm ................................................................................................}$ \\ \\
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-\\ +What happens if you short-circuit $R_2$ (the feedback resistor)?\\ 
-\\ +Experimentally verify this effect and explain the observed behavior regarding the output voltage.\\ 
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-\\ +${\rm ................................................................................................}$ \\ \\ 
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-$I_{\rm 1}{\rm~=}$ +${\rm ................................................................................................}$ \\ \\ 
-\\ +${\rm ................................................................................................}$ \\ \\
-\\ +
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-$I_{\rm 2}{\rm~=}$ +
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-$I_{\rm N12}{\rm~=}$ +
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-- Virt masse messen\\ +
-- r2 kurzschluss+