US 6,972,588 B1 · Adjustable differential input and output drivers

Abstract

Systems and methods are provided using common-mode-voltage bias circuitry to make common-mode-voltage adjustments to differential driver circuitry in integrated circuit differential communications links. Adjustable bias circuitry may be controlled using static and dynamic control signals. Dynamic control signals can be produced by core logic on a programmable logic device or other integrated circuit. Static control signals can be produced by programmable elements. Bias circuit adjustments made at one end of a differential link can be used to improve performance at either end of the link or can be used to improve power consumption or to balance power and performance considerations. The same integrated circuit design can be used in both AC-coupled and DC-coupled environments. The bias circuitry can be formed from an adjustable current source and adjustable resistor. The current source and adjustable resistors can be controlled by the same control signals.

Claims20

Dependent claims

A method of using an integrated circuit to support communications over a differential communications link, wherein the integrated circuit includes input-output circuitry with differential input drivers and differential output drivers and programmable core logic and wherein the input-output circuitry includes input driver common-mode-voltage bias circuitry and output driver common-mode-voltage bias circuitry, the method comprising:

using the programmable core logic to produce data signals for the input-output circuitry and to receive data signals from the input-output circuitry;
using the input driver common-mode-voltage bias circuitry in the input-output circuitry to adjust common-mode-voltage levels at the input drivers;
and
using the output driver common-mode-voltage bias circuitry in the input-output circuitry to adjust common-mode-voltage levels at the output drivers.

1 more element

An integrated circuit differential driver circuit on an integrated circuit that communicates with another integrated circuit using a differential communications path over which differential data signals are conveyed, comprising:

a differential driver that is connected to the differential communications path and through which the differential data signals are passed, wherein the differential driver has a desired common-mode-voltage operating range;
and
adjustable common-mode-voltage bias circuitry coupled to the differential driver that is adjusted so that the differential data signals passing through the differential driver have a common-mode voltage level within the desired common-mode-voltage operating range, wherein the common-mode-voltage bias circuitry includes an adjustable resistor and an adjustable current source that are controlled by static control signals provided on the integrated circuit.

Dependencies are inferred from the claim text.

Adjustable differential input and output drivers

Life of this patent

Adjustable differential input and output drivers

Life of this patent

Abstract

Claims20