Transmission line driver and method for driving the same
AssigneeRealtek Semiconductor Corp.
InventorSu-liang Liao
Life of this patent
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Abstract
A transmission line driver and a method for driving the same are provided, in which a composite current source is provided as an input current source, such that an output voltage is fixed. The composite current source includes an internal current source and an external current source. The composite current source is supplied to a single-ended transmission line driver or a differential transmission line driver, such that the output voltage is fixed.
Claims10
A transmission line driver implemented in an integrated circuit (IC), for driving a transmission line having a load impedance, comprising:
- a composite current source, comprising:
- an internal current source, generated by a voltage and an internal reference resistor, wherein a value of the internal reference resistor is set during manufacturing of the IC;
- and
- an external current source, generated by the voltage and an external reference resistor;
- and
- a gain circuit, coupled to the composite current source, for generating an output voltage, and driving the transmission line by providing the output voltage through the load impedance, wherein the gain circuit is a differential gain circuit that comprises:
- a first impedance pair, having one end respectively coupled to two ends of the composite current source;
- an amplifier, having a pair of input ends and a pair of output ends, wherein the pair of input ends is respectively coupled to the two ends of the composite current source, and the pair of output ends is respectively coupled to the other end of the first impedance pair;
- a second impedance pair, having an impedance coupled between one output end of the amplifier and one end of the load impedance, and the other impedance coupled between the other output end of the amplifier and the other end of the load impedance;
- and
- a third impedance pair, having an impedance coupled between one input end of the amplifier and one end of the load impedance, and the other impedance coupled between the other input end of the amplifier and the other end of the load impedance.
A method for driving a transmission line having a load impedance via a transmission line driver implemented in an integrated circuit (IC), comprising:
- providing a composite current for a gain circuit to generate an output voltage, wherein the composite current comprises an internal current part and an external current part;
- and
- driving the transmission line by providing the output voltage through the load impedance;
- wherein the internal current part is generated according to an internal reference resistor, and the external current part is generated according to an external reference resistor, wherein a value of the internal reference resistor is set during manufacturing of the IC, wherein the gain circuit is a differential gain circuit that comprises:
- a first impedance pair, having one end respectively coupled to two ends of the composite current source;
- an amplifier, having a pair of input ends and a pair of output ends, wherein the pair of input ends is respectively coupled to the two ends of the composite current source, and the pair of output ends is respectively coupled to the other end of the first impedance pair;
- a second impedance pair, having an impedance coupled between one output end of the amplifier and one end of the load impedance, and the other impedance coupled between the other output end of the amplifier and the other end of the load impedance;
- and
- a third impedance pair, having an impedance coupled between one input end of the amplifier and one end of the load impedance, and the other impedance coupled between the other input end of the amplifier and the other end of the load impedance.
Dependencies are inferred from the claim text.