User:Omegatron/opamps
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Common Configurations (with breaks)
The resistors used in these configurations are typically in the kΩ range. <1 kΩ range resistors cause excessive current flow and possible damage to the device. >1 MΩ range resistors cause excessive thermal noise and bias currents.
Zout for all of the amplifiers is ideally 0 Ω. Realistically, it is 1 Ω to 1 kΩ, depending on the device.
Inverting amplifier
Missing image
Opampinverting.png
Inverting Amplifier
- Inverts and amplifies a voltage (multiplies by a negative constant)
- Vout = −Vin (Rf / Rin)
- Zin = Rin (because V− is a virtual ground)
Non-inverting amplifier
Missing image
Opampnoninverting.png
Non-Inverting Amplifier
- Amplifies a voltage (multipies by a constant greater than 1)
- Vout = Vin (1 + R2 / R1)
- Zin = ∞ (realistically, the input impedance of the op-amp itself, 1 MΩ to 1012 Ω)
Voltage follower
Missing image
Opampfollowing.png
Voltage Follower
- Used as a buffer, to eliminate loading effects or to interface impedances (connecting a device with a high source impedance to a device with a low input impedance)
- Vout = Vin
- Zin = ∞ (realistically, the input impedance of the op-amp itself, 1 MΩ to 1012 Ω)
Difference amplifier
- For independent R1,R2,R3,R4 (differential amplifier):
- <math> V_{out} = V_2 \left( { \left( R_3 + R_1 \right) R_4 \over \left( R_4 + R_2 \right) R_1} \right) - V_1 \left( {R_3 \over R_1} \right) <math>
- For R1 = R2 and R3 = R4 (amplified difference),
- <math> V_{out} = {R_3 \over R_1} \left( V_2 - V_1 \right) <math>
- For R1 = R3 and R2 = R4 (also for R1 = R2 = R3 = R4) (difference amplifier):
- <math> V_{out} = V_2 - V_1 \,\!<math>
- Differential Zin (between the two input pins) = R1 + R2
- An instrumentation amplifier is made by adding a voltage follower to each input to increase the input impedance.
Summing amplifier
- Sums several (weighted) voltages
- Output is inverted
- For independent R1, R2, ... Rn
- V = − Rf (V1 / R1 + V2 / R2 + ... + Vn / Rn)
- For R1 = R2 = ... = Rn, and RF independent
- V = − (Rf / R1) (V1 + V2 + ... + Vn)
- For R1 = R2 = ... = Rn = Rf
- V = − (V1 + V2 + ... + Vn)
- Input impedance Zn = Rn, for each input (V− is a virtual ground)
Integrator
- Integrates the signal over time (where Vin and Vout are functions of time)
- <math> V_{out} = \int_0^t - {V_{in} \over RC} \, dt + V_{initial} <math>
(Vinitial is the output voltage of the integrator at time t = 0.) - Note that this can also be viewed as a type of electronic filter.
Differentiator
Missing image
Opampdifferentiating.png
Differentiating Amplifier
- Differentiates the signal over time (where Vin and Vout are functions of time)
- <math> V_{out} = - R C \, {d V_{in} \over dt} <math>
- Note that this can also be viewed as a type of electronic filter.
Comparator
Missing image
Opampcomparator.png
Comparator
- Compares two voltages and outputs one of two states depending on which is greater
- <math> V_{out} = \left\{\begin{matrix} V_{S+} & V_1 > V_2 \\ V_{S-} & V_1 < V_2 \end{matrix}\right. <math>
- See article for details
- A comparator with hysteresis
- See article for details
- Simulates an inductor
- See article for details
Common Configurations (with headers)
The resistors used in these configurations are typically in the kΩ range. <1 kΩ range resistors cause excessive current flow and possible damage to the device. >1 MΩ range resistors cause excessive thermal noise and bias currents.
Zout for all of the amplifiers is ideally 0 Ω. Realistically, it is 1 Ω to 1 kΩ, depending on the device.
Inverting amplifier
Missing image
Opampinverting.png
Inverting Amplifier
- Inverts and amplifies a voltage (multiplies by a negative constant)
- Vout = −Vin (Rf / Rin)
- Zin = Rin (because V− is a virtual ground)
Non-inverting amplifier
Missing image
Opampnoninverting.png
Non-Inverting Amplifier
- Amplifies a voltage (multipies by a constant greater than 1)
- Vout = Vin (1 + R2 / R1)
- Zin = ∞ (realistically, the input impedance of the op-amp itself, 1 MΩ to 1012 Ω)
Voltage follower
Missing image
Opampfollowing.png
Voltage Follower
- Used as a buffer, to eliminate loading effects or to interface impedances (connecting a device with a high source impedance to a device with a low input impedance)
- Vout = Vin
- Zin = ∞ (realistically, the input impedance of the op-amp itself, 1 MΩ to 1012 Ω)
Difference amplifier
- For independent R1,R2,R3,R4 (differential amplifier):
- <math> V_{out} = V_2 \left( { \left( R_3 + R_1 \right) R_4 \over \left( R_4 + R_2 \right) R_1} \right) - V_1 \left( {R_3 \over R_1} \right) <math>
- For R1 = R2 and R3 = R4 (amplified difference),
- <math> V_{out} = {R_3 \over R_1} \left( V_2 - V_1 \right) <math>
- For R1 = R3 and R2 = R4 (also for R1 = R2 = R3 = R4) (difference amplifier):
- <math> V_{out} = V_2 - V_1 \,\!<math>
- Differential Zin (between the two input pins) = R1 + R2
- An instrumentation amplifier is made by adding a voltage follower to each input to increase the input impedance.
Summing amplifier
- Sums several (weighted) voltages
- Output is inverted
- For independent R1, R2, ... Rn
- V = − Rf (V1 / R1 + V2 / R2 + ... + Vn / Rn)
- For R1 = R2 = ... = Rn, and RF independent
- V = − (Rf / R1) (V1 + V2 + ... + Vn)
- For R1 = R2 = ... = Rn = Rf
- V = − (V1 + V2 + ... + Vn)
- Input impedance Zn = Rn, for each input (V− is a virtual ground)
Integrator
- Integrates the signal over time (where Vin and Vout are functions of time)
- <math> V_{out} = \int_0^t - {V_{in} \over RC} \, dt + V_{initial} <math>
(Vinitial is the output voltage of the integrator at time t = 0.) - Note that this can also be viewed as a type of electronic filter.
Differentiator
Missing image
Opampdifferentiating.png
Differentiating Amplifier
- Differentiates the signal over time (where Vin and Vout are functions of time)
- <math> V_{out} = - R C \, {d V_{in} \over dt} <math>
- Note that this can also be viewed as a type of electronic filter.
Comparator
Missing image
Opampcomparator.png
Comparator
- Compares two voltages and outputs one of two states depending on which is greater
- <math> V_{out} = \left\{\begin{matrix} V_{S+} & V_1 > V_2 \\ V_{S-} & V_1 < V_2 \end{matrix}\right. <math>
- See article for details
Schmitt trigger
- A comparator with hysteresis
- See article for details
Inductance gyrator
- Simulates an inductor
- See article for details