Method and apparatus for parallel in serial out transmission
AssigneeATI Technologies, Inc.
InventorsEdward Chak Cheung Ho, Nancy Ngar Sze Chan, Hugh Hin-Poon Chow
Life of this patent
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Abstract
A method and apparatus for providing serial transmission of a parallel input is accomplished by a parallel input serial output transmitter that includes a shift register operably coupled to receive a parallel input and to provide data serially to a gating circuit. The gating circuit, based on the state of the data it receives, generates a drive signal which causes a switching circuit to route current from first and second current sources to a third current source over different paths to produce a serial output. A bias circuit is coupled to the switching circuit to bias the serial output to a desired level.
Claims20
A parallel input serial output transmitter, comprising:
- a shift register that is operably coupled in parallel to receive a plurality of digital bits;
- a switching circuit having two switch elements inter-operatively coupled to provide a serial output for the plurality of digital bits;
- a gating circuit operably coupled to the shift register and the switching circuit, the gating circuit providing at least two drive signals to the gating circuit at a rate corresponding to a data rate;
- a first current source operably coupled to the switching circuit and a supply voltage source, and a second current source operably coupled to the switching circuit and the supply voltage source;
- a third current source operably coupled to the switching circuit and a supply return;
- and
- a bias circuit operably coupled to provide a bias voltage to the switching circuit.
A video graphics circuit comprising:
- display engine that processes display data based on display operational instructions;
- memory controller operably coupled to the display engine and to read/write data from/to an external memory;
- graphic user interface engine operably coupled to the memory controller;
- peripheral card interface operably coupled to the graphic user interface and the memory controller;
- an LCD engine operably coupled to the display engine;
- and
- a parallel input serial output transmitter operably coupled to the LCD engine comprising:
- a shift register that is operably coupled in parallel to receive a plurality of digital bits;
- a switching circuit having two switch elements inter-operatively coupled to provide a serial output for the plurality of digital bits;
- a gating circuit operably coupled to the shift register and the switching circuit, the gating circuit providing at least two drive signals to the gating circuit at a rate corresponding to a data rate;
- a first current source operably coupled to the switching circuit and a supply voltage source, and a second current source operably coupled to the switching circuit and the supply voltage source;
- a third current source operably coupled to the switching circuit and a supply return;
- and
- a bias circuit operably coupled to provide a bias voltage to the switching circuit.
A parallel input serial output transmitter, comprising:
- a shift register that is operably coupled in parallel to receive a plurality of digital bits;
- a switching circuit having first and second switching transistors inter-operatively coupled to provide a serial output for the plurality of digital bits;
- a gating circuit operably coupled to the shift register and the switching circuit, the gating circuit providing at least two drive signals to the gating circuit at a rate corresponding to a data rate;
- a first current source operably coupled to the first transistor in the switching circuit and to a supply voltage source, and a second current source operably coupled to the second transistor in the switching circuit and to the supply voltage source;
- a third current source operably coupled to the first and second switching transistors in the switching circuit and to a supply return;
- and
- a bias circuit operably coupled to provide a bias voltage to the switching circuit.
Dependencies are inferred from the claim text.