Circuit for a transceiver output port of a local area networking device
AssigneeRealtek Semiconductor Corp.
InventorChen-Chih Huang
Life of this patent
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Abstract
A driving circuit for a transceiver output port of a local area networking device is provided, including first and second current sources coupled to the ground, first and second resistors coupled to the supply voltage with the resistances of the first and second resistors each being equal to half that of the equivalent resistance of the cable for the purpose of impedance matching, and third and fourth current sources coupled to the cable for providing additional currents while the first and second current sources are operating such that the magnitude of the differential output signal is determined not only according to the first and second currents but also according to the third and fourth currents.
Claims25
A driving circuit of a transceiver output port of a local area networking device, wherein the transceiver output port is coupled to a cable and the driving circuit is for outputting a differential output signal to the cable, the driving circuit comprising:
- a first output node;
- a second output node, wherein the first and second output nodes are for outputting the differential output signal;
- a first current source coupled to the first output node for providing a first current;
- a second current source coupled to the second output node for providing a second current;
- a first resistor coupled to the first output node;
- a second resistor coupled to the second output node;
- a third current source coupled between the first output node and a supply voltage source for providing a third current;
- and
- a fourth current source coupled between the second output node and the supply voltage source for providing a fourth current;
- wherein the resistance of the first resistor and the resistance of the second resistor each are equal to ½ of the equivalent resistance of the cable for the purpose of impedance matching to the cable, and
- wherein the third and fourth current sources are used for providing currents while the first and second current sources are operating such that the magnitude of the differential output signal is determined not only according to the first and second currents but also according to the third and fourth currents.
A driving circuit for a transceiver output port of a local networking device, the local networking device including first and second output nodes for communicating with a cable coupled between the first and second output nodes, for providing a differential output signal, the driving circuit comprising:
- a supply voltage source for providing a supply voltage;
- a first current source coupled between the first output node and ground;
- a second current source coupled between the second output node and ground;
- wherein the resistor unit includes a first resistor coupled to the first output node and a second resistor coupled to the second output node;
- a third current source coupled between the first output node and the supply voltage source;
- a fourth current source coupled between the second output node and the supply voltage source;
- and
- wherein the magnitude of the differential output signal is determined not only according to the first and second currents but also according to the third and fourth currents.
A driving circuit for a transceiver output port of a local area networking device, the driving circuit comprising:
- first and second output nodes for outputting a differential output signal to a network cable;
- an equivalent output resistor that matches an impedance of the network cable, wherein the equivalent output resistor comprises a first resistor and a second resistor for matching the impedance of the network cable;
- a supply voltage source for providing a supply voltage;
- a first current source coupled between the first output node and ground;
- a second current source coupled between the second output node and ground;
- a third current source coupled between the first output node and the supply voltage source;
- and
- a fourth current source coupled between the second output node and the supply voltage source;
- wherein the third and fourth current sources are used for providing currents while the first and second current sources are operating.
Dependencies are inferred from the claim text.