SLOA011B January   2018  – July 2021 LF347 , LF353 , LM348 , MC1458 , TL022 , TL061 , TL062 , TL071 , TL072 , UA741

 

  1. 1Introduction
    1. 1.1 Amplifier Basics
    2. 1.2 Ideal Op Amp Model
  2. 2Non-Inverting Amplifier
    1. 2.1 Closed Loop Concepts and Simplifications
  3. 3Inverting Amplifier
    1. 3.1 Closed Loop Concepts and Simplifications
  4. 4Simplified Op Amp Circuit Diagram
    1. 4.1 Input Stage
    2. 4.2 Second Stage
    3. 4.3 Output Stage
  5. 5Op Amp Specifications
    1. 5.1  Absolute Maximum Ratings and Recommended Operating Condition
    2. 5.2  Input Offset Voltage
    3. 5.3  Input Current
    4. 5.4  Input Common Mode Voltage Range
    5. 5.5  Differential Input Voltage Range
    6. 5.6  Maximum Output Voltage Swing
    7. 5.7  Large Signal Differential Voltage Amplification
    8. 5.8  Input Parasitic Elements
      1. 5.8.1 Input Capacitance
      2. 5.8.2 Input Resistance
    9. 5.9  Output Impedance
    10. 5.10 Common-Mode Rejection Ratio
    11. 5.11 Supply Voltage Rejection Ratio
    12. 5.12 Supply Current
    13. 5.13 Slew Rate at Unity Gain
    14. 5.14 Equivalent Input Noise
    15. 5.15 Total Harmonic Distortion Plus Noise
    16. 5.16 Unity-Gain Bandwidth and Phase Margin
    17. 5.17 Settling Time
  6. 6References
  7. 7Glossary
  8. 8Revision History

5.7 Large Signal Differential Voltage Amplification

Large signal differential voltage amplification, AVD, is the ratio of the output voltage change to the input differential voltage change, while holding VCM constant. This parameter is closely related to the open loop gain. The difference is that it is measured with an output load and therefore takes into account loading effects.

The DC value of AVD is published in the data sheet, but AVD is frequency dependent. Figure 5-12 shows a typical graph of AVD vs. frequency.

AVD is a design issue when precise gain is required. Consider equation Equation 16, where the loop gain of the non-inverting amplifier is given by:

Equation 33. GUID-D1B84220-565D-4218-A718-17D4EE3A9C43-low.gif

where,

Equation 34. GUID-D34C4755-C61E-46E2-B1B0-D4C25D9D4F44-low.gif

It is desired to control the gain of the circuit by selecting the appropriate resistors. The term 1/ab in the equation is seen as an error term. Unless a, or AVD, is large in comparison with 1/b, it will have an undesired effect on the gain of the circuit.