Dynamically-adjustable differential output drivers

• US 7,397,270 B1
• Filed: 05/25/2005
• Issued: 07/08/2008
• Est. Priority Date: 09/24/2003
• Status: Expired due to Fees

• Current Assignee: Tahoe Research Limited (f/k/a Learndale Limited) (Vector Capital Corporation)
• Original Assignee: Altera Corporation (Intel Corporation)
• Inventors: Wong, Wilson, Shumarayev, Sergey, Lee, Chong H., Luo, Mei
• Primary Examiner(s): Tan; Vibol
• Application Number:
  US11/138,919
• Time in Patent Office: 1,140 Days
• Field of Search: 326/86, 326/115, 326/127, 327/108
• US Class Current: 326/32
• CPC Class Codes: H03K 19/00369 Modifications for compensating variations of temperature, supply voltage or other physical parameters
• CPC Class Codes: H03K 19/01812 with at least one differential stage
• CPC Class Codes: H03K 19/01837 programmable
• CPC Class Codes: H03K 19/018514 with at least one differential stage H03K19/018528 and H03K19/018542 take precedence
• CPC Class Codes: H03K 19/018585 programmable

Abstract

Systems and methods are provided using dynamically adjustable differential output drivers. Integrated circuits such as programmable logic devices may be provided with adjustable differential output drivers for transmitting high-speed data to other integrated circuits. The peak-to-peak output voltage and common-mode voltage of the output drivers may be adjusted. Dynamic control circuitry may be used to control the settings of current sources, programmable resistors, and voltage source circuitry in the adjustable differential output driver automatically in real time. The adjustable components in the differential output driver may be adjusted by the dynamic control circuitry based on feedback information received from the integrated circuit to which the data is transmitted.

Claims

1. Dynamically adjustable differential output driver circuitry on an integrated circuit that transmits differential output data signals that have a peak-to-peak output voltage swing V_OD, comprising:

adjustable current source circuitry;

adjustable resistor circuitry;

switching circuitry for switching current from the adjustable current source circuitry through the adjustable resistor circuitry to produce the differential output signals, wherein the adjustable current source circuitry and adjustable resistor circuitry are controlled independently in real time by control signals to adjust the peak-to-peak output voltage swing V_OD of the differential output data signals; and

dynamic control circuitry that generates the control signals, wherein the dynamic control circuitry is implemented at least partly using programmable logic circuitry, wherein the resistor circuitry comprises process and temperature compensation circuitry to compensate for process-induced and temperature-induced resistivity changes in the resistor circuitry, wherein the resistor circuitry comprises a plurality of variable resistors, and wherein each variable resistor comprises a plurality of parallel paths each having an associated resistor.

2. An integrated circuit having:

an adjustable differential output driver that produces differential output data signals having a common mode voltage that are transmitted to another integrated circuit; and

control circuitry that controls the adjustable differential output driver to adjust the common mode voltage in response to feedback received from the other integrated circuit, wherein the adjustable differential output driver includes adjustable programmable resistor circuitry and programmable current source circuitry that are independently adjusted.

3. The integrated circuit defined in claim 2 further comprising programmable core logic.

4. The integrated circuit defined in claim 2 further comprising programmable core logic in which at least part of the control circuitry is implemented.

5. An integrated circuit having:

an adjustable differential output driver that produces differential output data signals having a common mode voltage that are transmitted to another integrated circuit; and

control circuitry that controls the adjustable differential output driver to adjust the common mode voltage in response to feedback received from the other integrated circuit, wherein the control circuitry comprises control circuitry that controls the adjustable differential output driver to adjust the common mode voltage in response to information that is based at least partially on a mismatch between the common mode voltage of the differential output data signals produced by the adjustable differential output driver at the integrated circuit and a common mode voltage measured for the differential output data signals when the differential output data signals are received at the other integrated circuit.

6. The integrated circuit defined in claim 5 wherein the adjustable differential output driver includes adjustable programmable resistor circuitry.

7. The integrated circuit defined in claim 5 wherein the adjustable differential output driver includes adjustable programmable current source circuitry.

8. The integrated circuit defined in claim 5 wherein the adjustable differential output driver includes adjustable programmable resistor circuitry and programmable current source circuitry.

9. An integrated circuit having:

an adjustable differential output driver that produces differential output data signals having a common mode voltage that are transmitted to another integrated circuit; and

control circuitry that controls the adjustable differential output driver to adjust the common mode voltage in response to feedback received from the other integrated circuit, wherein the control circuitry comprises control circuitry that uses the feedback to adjust the adjustable differential output driver to match the common-mode voltage of the differential output data signals to a common-mode voltage level for an input driver on the other integrated circuit.

10. An integrated circuit having:

an adjustable differential output driver that produces differential output data signals having a common mode voltage that are transmitted to another integrated circuit; and

control circuitry that controls the adjustable differential output driver to adjust the common mode voltage in response to feedback received from the other integrated circuit, wherein the differential output driver sends the differential output signals over a differential data channel to the other integrated circuit and wherein there are a plurality of such differential data channels between the integrated circuit and the other integrated circuit, each channel having its own associated level of peak-to-peak output voltage swing for its associated differential output data signals, wherein the control circuitry independently adjusts the differential output driver in each channel to adjust the level of the peak-to-peak output voltage swing for each channel.

11. An integrated circuit having:

an adjustable differential output driver that produces differential output data signals having a common mode voltage that are transmitted to another integrated circuit; and

control circuitry that controls the adjustable differential output driver to adjust the common mode voltage in response to feedback received from the other integrated circuit, wherein the adjustable differential output driver sends the differential output signals over a differential data channel to the other integrated circuit and wherein there are a plurality of such differential data channels between the integrated circuit the other integrated circuit, each channel having its own associated common-mode voltage for its associated differential output data signals, wherein the control circuitry independently adjusts the differential output driver in each channel to adjust the common-mode voltage for each channel.