Low power low voltage differential signaling (lvds) output drivers
AssigneeTexas Instruments Incorporated
InventorJohn Fattaruso
Life of this patent
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Abstract
A method and apparatus for providing a low power low voltage differential signaling driver are disclosed. In an example, a low voltage differential signaling driver circuit is described, comprising a first current source to provide current to a first differential pair of PNP transistors, a pair of transresistance amplifiers driven by a corresponding pair of transconductance stages, a second current source to provide current to a second differential pair of PNP transistors, and an output port having a common mode output voltage and a differential output voltage based on a state of the first differential pair of PNP transistors and the second differential pair of PNP transistors.
Claims15
A low voltage differential signaling driver circuit, the circuit comprising:
- a first differential pair of PNP transistors;
- a pair of transconductances stages;
- a second differential pair of PNP transistors that is coupled to the pair of transconductances stages;
- a first current source that is coupled to the first differential pair to provide current to the first differential pair;
- a second current source that is coupled to the second differential pair to provide current to the second differential pair;
- a pair of transresistance amplifiers that is coupled to the first differential pair and that is driven by the pair of transconductance stages;
- and
- an output port having a common mode output voltage and a differential output voltages, wherein each of the common mode output voltage and the differential output voltage is based on a state of the first differential pair and the second differential pair.
(canceled)
A method to provide low voltage differential signaling, the method comprising the steps of:
- increasing current flowing through a first differential transistor;
- decreasing current flowing through a second differential transistor;
- decreasing current flowing through a first transconductance stage to increase current flowing through a first transresistance amplifier;
- increasing current flowing through a second transconductance stage to decrease current flowing through a second transresistance amplifier;
- and
- transmitting a differential output signal by controlling one of the first or second differential transistor and one of the first or second transresistance amplifier.
A low voltage differential signaling driver circuit, the circuit comprising:
- a differential input;
- a bias input;
- a differential output;
- a first differential pair of PNP bipolar transistors, wherein each of the PNP transistors of the first differential pair is coupled to the differential input, and wherein the first differential pair is coupled to the differential output;
- a second differential pair of PNP bipolar transistors, wherein each of the PNP transistors of the second differential pair is coupled to the differential input;
- a first PNP current source coupled to the first differential pair;
- a second PNP current source coupled to the second differential pair;
- a pair of transresistance amplifiers coupled to the first differential pair, wherein the pair of transresistance amplifiers having local resistive feedback;
- a pair of current mirrors coupled the second differential pair to control the transresistance amplifiers;
- a common mode feedback block coupled between at least one of the current mirrors and the differential output.
Dependencies are inferred from the claim text.