Differential Amplifier

Here is a MOSFET Differential Amplifier circuit from Microelectronics Sedra Smith text Figure 9.3. No matter what voltage provided at the Gate of these transistors, the current split will not waver. This is a characteristic that gives Differential Amplifiers their immunity to CMN, and thus have a measurable CMRR. In my Current Switch/Differential Pair circuits, all of the current switches from one side or the other. I am led to believe that this skews the qualities of the CMR. I am also led to believe (Lee Ritchey CH31) that this is the key difference, that differentiates the Differential Amplifier in Analog Electronics and the Differential Pair configuration often seen and also called Differential Amplifiers (despite operating differently). Comment below your thoughts and please let me know if there is an error in my circuit configuration. Agree? Disagree?

published 2 years ago