Write driver with improvements for risetime

A write driver circuit for providing current through a transducer in an information storage system having first and second voltage supply terminals and first and second data input terminals, the write driver circuit comprising:

• an H-switch connected to the first and second voltage supply terminals and to the first and second data input terminals, the H-switch having a pair of pull-up transistors and a pair of pull-down transistors, each pull-down transistor has a base, a collector and an emitter and wherein the collector of each pull-down transistor is connected to one of the pull-up transistors and the emitter of the pull-down transistor is connected to the second voltage supply terminal through only a load;
• a biasing circuit connected to the base of each of the pull-down transistors to bias the pull-down transistors;
• and
• an anti-saturation circuit connected to each of the pull-up transistors to bias the pull-up transistors, wherein the anti-saturation circuit contains at least one transistor having a collector, a base and an emitter and wherein a pair of diodes having an anode and a cathode are connected between the base and the collector of the at least one transistor, wherein the cathodes of the diodes are connected together and wherein the diodes have substantially similar characteristics.

A write driver circuit for providing current through a transducer in an information storage system having first and second voltage supply terminals and first and second data input terminals, the write driver circuit comprising:

• an H-switch connected to the first and second voltage supply terminals and to the first and second data input terminals, the H-switch having a pair of pull-up transistors and a pair of pull-down transistors;
• a first and second anti-saturation driver circuit connected to each of the pull-up transistors that operate in opposite directions to bias the pull-up transistors, wherein first and second current supplies are connected to the first and second anti-saturation driver circuits to provide current thereto, and wherein each of the first and second anti-saturation driver circuits contain first and second anti-saturation transistors having a collector, a base and an emitter, first and second diodes having an anode and a cathode, and a resistor, wherein the first and second diodes are connected between the base and the collector of the first anti-saturation transistor and wherein the cathodes of the first and second diodes are connected together and wherein the diodes have substantially similar characteristics;
• and
• a separate biasing circuit connected to each of the pull-down transistors to bias the pull-down transistors.