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Non-Ideal Operational Amplifiers and Feedback Stability - Coggle Diagram
Non-Ideal Operational Amplifiers and Feedback Stability
DC Error Sources and Output Range Limitations
Input-Offset Voltage
Definition: The voltage needed to make the output zero when inputs are grounded.
Effect on Performance: Causes errors in precision applications.
Mitigation: Adjust or trim the offset.
Input-Bias and Offset Currents
Input Bias Current
Definition: Average current entering the input terminals.
Effect: Can cause voltage errors across resistive components.
Common-Mode Rejection Ratio (CMRR)
Finite CMRR
Definition: Ratio of differential gain to common-mode gain.
Importance: Ensures the op-amp amplifies differential signals while ignoring common-mode noise.
Finite CMRR Effects: Imperfect rejection of common-mode signals.
Why CMRR is Important
Signal Integrity
Noise Rejection: Prevents unwanted signals from being amplified.
Clear Signal Processing: Essential for accurate signal processing in noisy environments.
Precision
Differential Measurements: Accurate readings depend on high CMRR.
Minimizing Errors: High CMRR reduces errors from power supply noise.
11.11 DC Error Sources and Output Range Limitations
11.11.1 Input-Offset Voltage
Definition: The differential DC voltage required between the input terminals of an op-amp to bring the output to zero when the inputs are grounded.
Effect on Performance: Can cause errors in low-signal applications due to voltage difference even when inputs should theoretically be zero.
11.11.3 Input-Bias and Offset Currents
Input Bias Current: The average current entering the input terminals of the op-amp.
Offset Current: The difference between the bias currents entering the two input terminals.
11.12.2 Why is CMRR Important?
Signal Integrity
high CMRR is crucial to ensuring that the op-amp amplifies the desired signal
without amplifying common-mode noise
Noise Rejection
High CMRR improves the ability to reject electromagnetic interference
power supply noise that can be present on both input lines