Low voltage differential swing (LVDS) signal driver circuit with low PVT sensitivity

• US 6,788,116 B1
• Filed: 07/26/2002
• Issued: 09/07/2004
• Est. Priority Date: 07/26/2002
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Yarbrough, Roy L., Cook, Richard W., OʼBrien, Stephen J.
• Primary Examiner(s): Lam, Tuan T.
• Assistant Examiner(s): Nguyen, Hiep
• Application Number:
  US10/205,853
• Time in Patent Office: 774 Days
• Field of Search: 327/108, 327/198, 326/30, 326/82, 326/83, 326/86, 326/87, 326/88, 326/89, 326/90, 345/204
• US Class Current: 327/108
• CPC Class Codes: H04L 25/0272 Arrangements for coupling to multiple lines, e.g. for differential transmission
• CPC Class Codes: H04L 25/028 Arrangements specific to the transmitter end

Abstract

A low voltage differential swing (LVDS) signal driver having a constant output differential voltage (Vod) over variations in circuit fabrication processes, power supply voltages and operating temperatures (PVT). The minimum and maximum values of the LVDS output signal are monitored and, based upon the difference between them, a signal is provided to the circuit to control the LVDS output signal such that its peak-to-peak value is maintained at a determined value.

Claims

1. An apparatus including a low voltage differential swing (LVDS) signal driver, comprising:

differential signal driver circuitry that receives a control signal and in response thereto receives and converts a dual differential input signal to a LVDS signal having minimum and maximum peak signal values; and

feedback circuitry, coupled to said differential signal driver circuitry, that receives said LVDS signal and in response thereto provides said control signal, wherein a difference between said minimum and maximum peak signal value, is maintained at a predetermined value;

wherein said feedback circuitry comprises

signal peak detection circuitry that receives said LVDS signal and in response thereto provides first and second detected peak signals representing said minimum and maximum peak signal values, and

control circuitry, coupled to said signal detection circuitry, that receives said first and second detected peak signals and in response thereto provides said control signal.

2. The apparatus of claim 1, wherein said signal peak detection circuitry comprises first and second peak signal detectors that detect said minimum and maximum peak signal values and in response thereto provides said first and second detected peak signals.

3. The apparatus of claim 1, wherein said control circuitry comprises signal combining circuitry that receives and differentially combines said first and second detected peak signals to provide a difference signal.

4. The apparatus of claim 3, wherein said control circuitry further comprises signal comparison circuitry, coupled to said signal combining circuitry, that receives and compares a reference signal and said difference signal and in response thereto provides said control signal.

5. The apparatus of claim 1, wherein said differential signal driver circuitry comprises:

current source circuitry that receives said control signal and in response thereto provides a driver current; and

differential amplifier circuitry, coupled to said current source circuitry, that receives said dual differential input signal and in response thereto selectively conducts said driver current to produce said LVDS signal.

6. An apparatus including a low voltage differential swing (LVDS) signal driver, comprising:

signal driver means for receiving a control signal and in response thereto receiving and converting a dual differential input signal to a LVDS signal having minimum and maximum peak signal values; and

feedback means for receiving said LVDS signal and in response thereto providing said control signal and maintaining difference between said minimum and maximum peak signal values at a predetermined value;

wherein said feedback means comprises

peak detector means for detecting said LVDS signal and providing first and second detected peak signals representing said minimum and maximum peak signal values, and

controller means for receiving said first and second detected peak signals and in response thereto providing said control signal.

7. The apparatus of claim 6, wherein said signal driver means comprises:

current sourcing means for receiving said control signal and in response thereto providing a driver current; and

amplifier means for receiving said dual differential input signal and in response thereto selectively conducting said driver current and producing said LVDS signal.

8. A method for generating a low voltage differential swing (LVDS) signal driver, comprising:

receiving a control signal;

receiving a dual differential input signal;

converting said dual differential input signal to a LVDS signal having minimum and maximum peak signal values in response to said control signal; and

generating said control signal in response to said LVDS signal and thereby maintaining a difference between said minimum and maximum peak signal values at a predetermined value by

generating, in response to said LVDS signal, first and second detected peak signals representing said minimum and maximum peak signal values, and

generating said control signal in response to said first and second detected peak signals.

9. The method of claim 8, wherein said generating, in response to said LVDS signal, first and second detected peak signals representing said minimum and maximum peak signal values comprises:

detecting said minimum and maximum peak signal values; and

generating, in response to said detection, said first and second detected peak signals.

10. The method of claim 8, wherein said generating said control signal in response to said first and second detected peak signals comprises generating, in response to a difference between said first and second detected peak signals, a difference signal as said at least one resultant signal.

11. The method of claim 10, wherein said generating said control signal in response to said at least one resultant signal comprises:

receiving a reference signal;

comparing said reference signal and said difference signal; and

generating said control signal in response to said comparison.

12. The method of claim 8, wherein said converting said dual differential input signal to a LVDS signal having minimum and maximum peak signal values in response to said control signal comprises:

generating a driver current in response to said control signal; and

selectively conducting said driver current in response to said dual differential input signal to produce said LVDS signal.