US 2006/0215769 A1 · Differential transmitter circuit

Abstract

A driver circuit is configured as a frequency compensated differential amplifier having one input coupled to a first data signal and a second input coupled to a second data signal. Each stage of the differential amplifier is biased with a current source. The driver circuit generates a first output signal coupled to the input of a first transmission line and a second output signal coupled to the input of a second transmission line. The first and second output signals are generated as the difference between the first and second data signals amplified by a compensated gain. A compensation network that attenuates the low frequency components of the input signals relative to the high frequency components is coupled between current sources biasing the differential amplifier. The outputs of the first and second transmission lines are coupled to the inputs of a differential receiver that may or may not be frequency compensated.

Claims20

Dependent claims

A driver circuit for transmitting a differential logic signal over transmission lines comprising:

a differential circuit having a first input coupled to a first data signal, a second input coupled to a second data signal, a first driver output with a first source resistance coupled to an input of a first transmission line and generating a first output signal, and a second driver output with a second source resistance coupled to an input of a second transmission line and generating a second output signal, wherein the first output signal is a difference between the first and second data signals amplified with a compensated gain, and the second output signal is a complement of the first output signal;
and
a driver compensation network coupled to the differential circuit for setting the compensated gain to have a maximum gain value for frequencies greater than a first frequency, attenuating the maximum gain value of the differential circuit to a minimum gain value at frequencies below a second frequency substantially lower than the first frequency, and setting the compensated gain of the amplifier to transition between the minimum and maximum gain values at frequencies between the first and second frequencies.

An integrated circuit (IC) driving transmission lines transmitting a multiplicity of logic signals to a receiving IC comprising:

a differential circuit having a first input coupled to a first data signal, a second input coupled to a second data signal, a first driver output with a first source resistance coupled to an input of a first transmission line and generating a first output signal, and a second driver output with a second source resistance coupled to an input of a second transmission line and generating a second output signal, wherein the first output signal is a difference between the first and second data signals amplified with a compensated gain, and the second output signal is a complement of the first output signal, and a driver compensation network coupled to the differential circuit for setting the compensated gain to have a maximum gain value for frequencies greater than a first frequency, attenuating the maximum gain value of the differential circuit to a minimum gain value at frequencies below a second frequency substantially lower than the first frequency, and setting the compensated gain of the amplifier to transition between the minimum and maximum gain values at frequencies between the first and second frequencies.

A data processing system comprising:

a central processing system (CPU);
a random access memory (RAM);
a bus coupling the CPU and the RAM;
and
an integrated circuit (IC) with differential drivers for driving transmission lines transmitting a multiplicity of differential signals to a receiving IC, the differential drivers having a differential circuit having a first input coupled to a first data signal, a second input coupled to a second data signal, a first driver output with a first source resistance coupled to an input of a first transmission line and generating a first output signal, and a second driver output with a second source resistance coupled to an input of a second transmission line and generating a second output signal, wherein the first output signal is a difference between the first and second data signals amplified with a compensated gain, and the second output signal is a complement of the first output signal, and a driver compensation network coupled to the differential circuit for setting the compensated gain to have a maximum gain value for frequencies greater than a first frequency, attenuating the maximum gain value of the differential circuit to a minimum gain value at frequencies below a second frequency substantially lower than the first frequency, and setting the compensated gain of the amplifier to transition between the minimum and maximum gain values at frequencies between the first and second frequencies.

2 more elements

Dependencies are inferred from the claim text.

Differential transmitter circuit

Life of this patent

Differential transmitter circuit

Life of this patent

Abstract

Claims20