Finite Common-Mode Rejection in Fully Differential Nonlinear Circuits

In this brief, it is highlighted that fully differential nonlinear circuits, even though perfectly symmetrical, can be significantly sensitive to common-mode (CM)/power-supply (PS) interference and can be affected by even-order distortion. The cross-modulation mechanism between CM and differential input components, which gives rise to such unwanted phenomena, is investigated both analytically and on the basis of computer simulations, and its impact on CM and PS rejection is compared with the effects of device mismatch.