ABSTRACT
To understand the procedures for measuring the OpAmp characteristics (determined by Lewis Method, or Loop of Tests), readers should be acquainted with the test circuits as well as with the definitions of the parameters. The test in low gain AC amplifiers, as audio amplifiers, comprises the application of a small signal at the input and the measurement of a large signal at the output. On the contrary, performing the test in high gain DC amplifiers, the inverse procedure applies: the output signal is allowed to sweep through a wide DC range and the resulting DC variation at the input is measured. To evaluate the Op‐Amp transfer function linearity, the gain test is sometimes performed in two stages. Instead of applying a single range of output signal variation, from -10 to +10 V, it can be split into two ranges: from 0 to +10 V and from 0 to -10 V.
