Abstract: A method, control apparatus, and system for re-establishing a common mode in a transmitter involve switching a driver circuit of the transmitter to a quick charge or quick discharge mode based on an output value of the transmitter. When the output later exceeds a programmable common mode voltage, the driver circuit is switched to a classical margining mode to bring the output back towards the targeted common mode voltage. The modes are switched by adjusting the number of activated pull-up and pull-down segments. More pull-up segments and less pull-down segments are activated in the quick charge mode than the classical margining mode. More pull-down segments and less pull-up segments are activated in the quick discharge mode than the classical margining mode.

Abstract: A system, method, and circuits for power efficient margining in a differential output driver that includes segments connected to outputs of the driver. Each segment can be configured independently to different states by activating corresponding transistor combinations. In a transmitting state, the transistors transmit data by establishing current paths between the driver outputs and a positive supply rail or a ground rail. In a margining state, the transistors are statically configured to form current paths that differ from those of the transmitting state, such that the segment contributes substantially a same differential impedance between the driver outputs as would be contributed by the segment when in the transmitting state, while contributing a different common mode impedance than in the transmitting state. The current paths of the margining state extend through transistors that transmit data in the transmitting state.