Patent ID: 7667540

Claim:
A class-AB driver having a signal input terminal AB IN and a signal output terminal AB OUT , comprising: a push-pull output stage coupled to the signal output terminal and wherein the push-pull output stage includes a first transistor M 1 having a first electrode, a second electrode and a control electrode and a second transistor M 2 having a first electrode, a second electrode, and a control electrode, and wherein the second electrode of M 1 and the first electrode of M 2 are coupled to the AB OUT ; a trans-linear loop including the push-pull output stage and wherein the trans-linear loop includes a third transistor M 3 having a first electrode, a second electrode and a control electrode, a fourth transistor M 4 having a first electrode, a second electrode and a control electrode, and a speed balancing resistor RB having an input and an output, wherein the control electrode of M 3 , the input of RB and the AB IN are coupled at node A, wherein the output of RB is coupled to the control electrode of M 1 at node B, and the second electrode of M 4 and the control electrode of M 2 are coupled at node C; an input stage coupled to the AB IN , and the trans-linear loop; and a current biasing and enabling circuit coupled to the input stage and the signal output terminal, wherein an upper signal path starting from the AB IN and arriving at the AB OUT via the node A, RB, and the node B and a lower signal path starting from the AB IN and arriving at the AB OUT via the node A and the node C have substantially similar signal travel time.