EEHDSGN Real Operational Amplifier Circuits
Introduction
Basic operational amplifier (op amp) circuits are covered to death elsewhere. What is commonly not discussed, however, is that real-world (industrial, rugged) op amp circuits are NOT the basic ones commonly shown everywhere.
Real-World Op Amp Circuit Considerations
Real-world considerations (for an op amp in an industrial / commercial product) include the following:
- Provisions to prevent op amp from oscillation.
- Provisions to include filtering on op am input.
- Provisions to balance op amp input impedances, especially when filtering is employed.
- Picking an appropriate op amp IC type for the project at hand.
- And many others.
Requisite Concepts
Input/output impedance
Single vs dual power supply rails
Distortion / Nonlinearity
Gain
Feedback
Basic Op Amp Circuits
It would be useful to start from basic circuits, and immediately observe issues with them:
TODO inverting
TODO its parameters
TODO non-inverting
TODO its parameters
TODO differential
TODO its parameters
Non-ideal op amp behaviors
Saturation
Operation close to rails
Nonlinearities
Bandwidth. Also non-linearity of bandwidth
Instability
Common-mode
Offset
Maximum output current
Preventing op amp oscillation
Adding filtering to op amp circuit
Impedance Balancing
Op amp features
Rail-to-rail input and/or output
Single-supply operation
Representative modern op amps for common applications
Rugged industrial designs requirements and concepts
Future part provision
Invariability over manufacturing changes, part changes, temperature, power supply voltage, etc
Gain selectability
Rugged industrial op amp circuits
Real-World considerations
Missing component / solder joint issues / component cracking
Contamination
Humidity
Tin whiskers
Part discontinuation (EOL)
