SLOA011B January 2018 – July 2021 LF347 , LF353 , LM348 , MC1458 , TL022 , TL061 , TL062 , TL071 , TL072 , UA741
Large signal differential voltage amplification, A_{VD}, is the ratio of the output voltage change to the input differential voltage change, while holding V_{CM} 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 A_{VD} is published in the data sheet, but A_{VD} is frequency dependent. Figure 5-12 shows a typical graph of A_{VD} vs. frequency.
A_{VD} 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:
where,
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 A_{VD}, is large in comparison with 1/b, it will have an undesired effect on the gain of the circuit.