PREEMPHASIS DRIVER WITH REPLICA BIAS
First Claim
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1. A system comprising:
- a replica driver that comprises a plurality of n-type digital-to-analog converter (NDAC) current sources, the replica driver being operable to produce a reference voltage based on current supplied by the NDAC current sources; and
a plurality of driver fingers that are coupled to the replica driver and each comprise a driver bias circuit and an output driver, the driver bias circuit comprising an operational amplifier (op-amp) that is operable to adjust current-source gate voltage in the output driver to produce voltages at output nodes of the driver fingers that approximately match the reference voltage produced by the replica driver.
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Abstract
In one embodiment, a system includes a replica driver that includes n-type digital-to-analog converter (NDAC) current sources. The replica driver can produce a reference voltage based on current supplied by the NDAC current sources. The system includes driver fingers that are coupled to the replica driver and each include a driver bias circuit and an output driver. The driver bias circuit includes an operational amplifier (op-amp) that can adjust current-source gate voltage in the output driver to produce voltages at output nodes of the driver fingers that approximately match the reference voltage produced by the replica driver.
33 Citations
25 Claims
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1. A system comprising:
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a replica driver that comprises a plurality of n-type digital-to-analog converter (NDAC) current sources, the replica driver being operable to produce a reference voltage based on current supplied by the NDAC current sources; and a plurality of driver fingers that are coupled to the replica driver and each comprise a driver bias circuit and an output driver, the driver bias circuit comprising an operational amplifier (op-amp) that is operable to adjust current-source gate voltage in the output driver to produce voltages at output nodes of the driver fingers that approximately match the reference voltage produced by the replica driver. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method comprising:
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by a replica driver that comprises a plurality of n-type digital-to-analog converter (NDAC) current sources, producing a reference voltage based on current supplied by the NDAC current sources; and by an operational amplifier (op-amp) in a driver bias circuit in each of a plurality of driver fingers that are coupled to the replica driver, adjusting current-source gate voltage in the output driver to produce voltages at output nodes of the driver fingers that approximately match the reference voltage produced by the replica driver. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A system comprising:
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a replica driver that comprises a plurality of n-type digital-to-analog converter (NDAC) current sources, the replica driver being operable to produce a low-output reference voltage (VOL) based on current supplied by the NDAC current sources; and a plurality of preemphasis driver fingers that are coupled to the replica driver and each comprise a driver bias circuit and a common gate (CG) driver, the driver bias circuit comprising an operational amplifier (op-amp) and a p-type digital-to-analog converter (PDAC) current source, the op-amp being operable to adjust current-source gate voltage in the CG driver to produce voltages at output nodes of the preemphasis driver fingers that approximately match VOL; wherein; each of the NDAC current sources corresponds to a particular one of the driver bias circuits, a first current of the NDAC current source mirroring a second current of the PDAC in the particular one of the driver bias circuits corresponding to the NDAC current source; and a replica bias circuit in the replica driver comprises a plurality of replica resistors, each replica resistor having a first resistance value that is a multiple of a second resistance value of a driver output resistor coupled to the output nodes of the driver fingers.
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Specification