Patent Document ID: 6111431
Application ID: 09078776
Patent Flag: 1

Claim One:
1. An apparatus including a line driver circuit for providing a differential signal to an external circuit, the line driver circuit comprising: first and second output nodes configured to couple to an external circuit and convey first and second drive currents; a current sourcing circuit configured to generate a third drive current; a current steering circuit coupled to the current sourcing circuit at a first signal node and coupled to the first and second output nodes and configured to receive first and second input signals and in accordance therewith direct the third drive current in first and second directions to provide the first and second drive currents, wherein the first and second drive currents together form at the first and second output nodes a differential output signal; a first regulating circuit coupled to the current sourcing circuit and to the current steering circuit; a current sinking circuit coupled to the current steering circuit at a second signal node; a second regulating circuit coupled to the current sinking circuit and to the current steering circuit; and a mimicking circuit coupled to the first and second regulating circuits and configured to provide a first reference signal to the first regulating circuit and a second reference signal to the second regulating circuit, wherein the first regulating circuit compares a first node signal at the first signal node with the first reference signal and when the first node signal transcends the first reference signal, controls the current sourcing circuit to source current to the current steering circuit to maintain a predetermined value of the differential output signal, and the second regulating circuit compares a second node signal at the second signal node with the second reference signal, and when the second node signal transcends the second reference signal, controls the current sinking circuit to sink current from the current steering circuit to maintain the predetermined value of the differential output signal.