Low comment mode impedence differential driver and applications thereof
First Claim
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1. A low common mode impedance differential driver comprises:
- an independent current source;
a switching module operably coupled to the independent current source, wherein taps in the switching module provide a differential output from an input;
a dependent current source operably coupled to the switching module; and
a bias control circuit operably coupled to the differential output and the dependent current source, wherein the bias control circuit provides a control signal to the dependent current source, which causes common mode of the differential output to be maintained within a desired tolerance.
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Abstract
A low common mode impedance differential driver includes an independent current source, a switching module, a dependent current source, and a bias control circuit. The independent and dependent current sources are operably coupled to the switching module to provide first and second current paths through the switching module. The bias control circuit is operably coupled to the dependent current source and to the differential output produced by the switching module. The bias control circuit provides a control signal to the dependent current source that causes the common mode of the differential output to be maintained within a desired tolerance.
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Citations
12 Claims
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1. A low common mode impedance differential driver comprises:
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an independent current source; a switching module operably coupled to the independent current source, wherein taps in the switching module provide a differential output from an input; a dependent current source operably coupled to the switching module; and a bias control circuit operably coupled to the differential output and the dependent current source, wherein the bias control circuit provides a control signal to the dependent current source, which causes common mode of the differential output to be maintained within a desired tolerance. - View Dependent Claims (2, 3, 4)
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5. A parallel to serial transmitter comprises:
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shift register operably coupled to receive a plurality of digital bits in parallel; gating circuitry operably coupled to the shift register to produce, in a serial manner, an input representative of each of the plurality of digital bits; an independent current source; a switching module operably coupled to the independent current source and the gating circuitry, wherein taps in the switching module produce a differential output from the input; a dependent current source operably coupled to the switching module; and a bias control circuit operably coupled to the differential output and the dependent current source, wherein the bias control circuit provides a control signal to the dependent current source, which causes common mode of the differential output to be maintained within a desired tolerance. - View Dependent Claims (6, 7, 8)
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9. A video graphics circuit comprises:
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a video graphics engine operably coupled to receive at least one of graphics data and video data, wherein the video graphics engine generates display data from the at least one of the graphics data and the video data, wherein color components of the display data are n-bits in length; and a parallel to serial transmitter operably coupled to the video graphics engine, wherein the parallel to serial transmitter includes; shift register operably coupled to receive a plurality of bits of the color components in parallel; gating circuitry operably coupled to the shift register to produce, in a serial manner, an input representative of each of the plurality of bits; an independent current source; a switching module operably coupled to the independent current source and the gating circuitry, wherein taps in the switching module produce a differential output from the input; a dependent current source operably coupled to the switching module; and a bias control circuit operably coupled to the differential output and the dependent current source, wherein the bias control circuit provides a control signal to the dependent current source, which causes common mode of the differential output to be maintained within a desired tolerance. - View Dependent Claims (10, 11, 12)
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Specification