Improvement of common-mode rejection ratio in symmetrical differential stages with dynamic load

The dynamic load structure for symmetrical differential stages based on principle of self-compensation of active elements small-signal parameters influence on common-mode rejection ratio (CMR) is proposed. Shown that this load in traditional stage structure allows to decrease influence of active elements transfer conductance on CMR. Limiting estimations that characterize CMR maximum are found. Results of simulation and comparative research of different symmetrical differential stages are given. Shown that different circuit approaches for CMR optimization are consistent.