Current-limiting in an amplifier system
AssigneeTexas Instruments Incorporated
InventorsDAIJIRO OTANI, KEITA IKAI
Life of this patent
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Abstract
One example includes an amplifier system. The system includes a gain stage configured to conduct a gain current in response to an input voltage. The system also includes a current limit stage coupled to the gain stage and being configured to one of source and sink the gain current and to define a limit amplitude of the gain current during a current limit condition. The system further includes an output stage coupled to the gain stage and configured to conduct an output current through an output node in response to the gain current, the output current having a maximum amplitude during the current limit condition that is proportional to the limit amplitude.
Claims21
A system comprising:
- a gain stage configured to conduct a gain current in response to an input voltage;
- a current limit stage coupled to the gain stage and being configured to one of source and sink the gain current and to define a limit amplitude of the gain current during a current limit condition;
- and
- an output stage coupled to the gain stage and configured to conduct an output current through an output node in response to the gain current, the output current having a maximum amplitude during the current limit condition that is proportional to the limit amplitude.
A voltage amplifier system comprising:
- a gain stage comprising a plurality of transistors configured to conduct at least one of a sinking current and a sourcing current in response to an input voltage;
- at least one current limit stage comprising a current mirror configured to provide the at least one of the sinking current and the sourcing current and to define a limit amplitude of the at least one of the sinking current and the sourcing current during a current limit condition;
- and
- an output stage coupled to the gain stage and configured to conduct an output current through an output node in response to the at least one of the sinking current and the sourcing current to provide an output voltage at the output node, the output current having a maximum amplitude during the current limit condition that is proportional to the limit amplitude.
A hard-disk drive (HDD) system comprising:
- a magnetic disk configured to store data;
- a spindle motor configured to control rotation of the magnetic disk;
- a head configured to write data to and read data from the magnetic disk;
- and
- a dual-stage actuator configured to cooperate with a voice coil motor to position the head with respect to the magnetic disk in response to an output voltage generated by an amplifier system amplitude during the current limit condition that is proportional to the limit.
The system of claim 21, wherein the input voltage is a differential input voltage comprising a first input voltage and a second input voltage, wherein the current limit stage comprises:
- a first current limit stage configured to sink the gain current through the gain stage based on a positive difference between the first input voltage and the second input voltage;
- and
- a second current limit stage configured to source the gain current through the gain stage based on a negative difference between the first input voltage and the second input voltage.
The system of claim 21, wherein the output stage comprises a source-follower arrangement of transistors, such that the output stage one of sources and sinks the output current provided out from or into the output node during a current limit condition.
The system of claim 21, wherein the current limit stage comprises a first transistor and a second transistor being arranged as a current mirror and a current source, wherein a predetermined current is provided from the current source through the first transistor, and wherein the second transistor is configured to one of source and sink the gain current based on the predetermined current through the first transistor.
Dependencies are inferred from the claim text.