LOW-VOLTAGE DIFFERENTIAL SIGNAL DRIVER FOR HIGH-SPEED DIGITAL TRANSMISSION

• US 20070279095A1
• Filed: 05/31/2006
• Published: 12/06/2007
• Est. Priority Date: 05/31/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Jiang, Jian Hong
• Granted Patent: US 7,579,872 B2
• Time in Patent Office: Days
• US Class Current: 326/83
• CPC Class Codes: H04L 25/0272 Arrangements for coupling to multiple lines, e.g. for differential transmission

Abstract

A low-voltage differential signal driver for high-speed digital transmission includes a first converter operable to receive a signal in a first type and convert the signal into a second type, wherein a resistance of the first converter is variable. A second converter couples to the first converter, the second converter is operable to receive a signal in the second type and convert the signal into the first type, wherein a resistance of the second converter is variable. The driver is operable to scale the resistance of the first and second converters to provide a constant ratio between the resistance of the first and second converters.

Claims

1. A low-voltage differential signal driver for high-speed digital transmission, comprising:

a first converter operable to receive a signal in a first type and convert the signal into a second type, wherein a resistance of the first converter is variable;

a second converter coupled to the first converter, the second converter operable to receive a signal in the second type and convert the signal into the first type, wherein a resistance of the second converter is variable;

wherein the driver is operable to scale the resistance of the first and second converters to provide a constant ratio between the resistance of the first and second converters.

2. The driver of claim 1, wherein:

the first converter comprises a plurality of switches operable to vary the resistance of the first converter; and

the second converter comprises a plurality of switches operable to vary the resistance of the second converter.

3. The driver of claim 2, wherein the plurality of switches in the first converter is operable to scale the resistance of the first converter to the resistance of the second converter.

4. The driver of claim 1, wherein the first and second converters each comprise a first set of one of more transistors coupled in parallel with a second set of one of more transistors, and a switch associated with each of the first and second sets, the switch operable to allow and prevent current flow through the first and second sets.

5. The driver of claim 1, wherein the signal in the first type is a digital signal, the signal in the second type is an analog signal, the first converter is a digital-to-analog converter, and the second converter is an analog-to-digital converter.

6. The driver of claim 1, wherein the first converter comprises a plurality of p-channel metal-oxide semiconductor field effect transistors.

7. The driver of claim 1, wherein the second converter comprises a plurality of n-channel metal-oxide semiconductor field effect transistors.

8. The driver of claim 1, wherein the first converter and the second converter are operable to drive signals at an Ethernet switch.

9. The driver of claim 1, further comprising a common-mode feedback circuit operable to control a common-mode voltage.

10. A method for driving a low-voltage differential signal driver for high-speed digital transmission, comprising:

varying a resistance of a first converter and a resistance of a second converter;

receiving a signal in a first type at the first converter;

converting the signal into a second type at the first converter;

receiving a signal in the second type at the second converter; and

converting the signal into the first type at the second converter, wherein varying the resistance of the first converter and the resistance of the second converter comprises scaling the resistance of the first and second converters to provide a constant ratio between the resistance of the first and second converters.

11. The method of claim 10, wherein scaling the resistance of the first and second converters comprises providing a constant resistive ratio between the first and second converters.

12. The method of claim 10, wherein the signal in the first type is a digital signal, and the signal in the second type is an analog signal.

13. The method of claim 10, further comprising driving signals at an Ethernet switch.

14. A system for driving a low-voltage differential signal driver for high-speed digital transmission, comprising:

means for varying a resistance of a first converter and a resistance of a second converter;

means for receiving a signal in a first type at the first converter;

means for converting the signal into a second type at the first converter;

means for receiving a signal in the second type at the second converter; and

means for converting the signal into the first type at the second converter, wherein varying the resistance of the first converter and the resistance of the second converter comprises scaling the resistance of the first and second converters to provide a constant ratio between the resistance of the first and second converters.

15. The system of claim 14, further comprising means for providing a constant resistive ratio between the first and second converters.

16. The system of claim 14, wherein the signal in the first type is a digital signal, and the signal in the second type is an analog signal.

17. The system of claim 14, further comprising means for driving signals at an Ethernet switch.