A CMOS Circuit Technique for Maintenance of the Common Mode Level in a Differential Output Pad Driver

In the unity gain feedback configuration, a MOS differential pair (MDP) with a current-mirror load is demonstrated to serve as an effective topology for maintenance of the dc common-mode level. HSPICE simulations as well as measurements obtained from a test vehicle indicated that the proposed topology allows control of the reference voltage in a driver whose performance satisfies the requirements of the IEEE low-voltage differential signaling (LVDS) standard. The potential application of this circuit technique in implementation of an output driver whose slew rate is controllable over a wide range of capacitive loads is also proposed.

Keywords:

Common mode level , Differential signaling , Current-mirror load , Unity gain feedback