On-chip calibrated source termination for voltage mode driver and method of calibration thereof
AssigneeVitesse Semiconductor Corporation
InventorsEric James Wyers, Dan Stiurea, John James Paulos
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Abstract
On-chip calibrated source termination for voltage mode driver. An amplifier is disclosed having an internal amplifier with a first output and a second output, the first output interfaced to a non-inverting input through an interface. The second output is coupled to the first output through a series resistance element. The output impedance of the amplifier is determined by the ratio of the current drive of the first and second outputs. The voltage on said second output being a function of said interface and the current input to said internal amplifier.
Claims85
An integrated circuit amplifier, comprising:
- an internal amplifier having a first output coupled to a non-inverting input through an interface-said
- said internal amplifier having a second output for providing an output signal from the integrated circuit with an associated output impedance;
- a series resistance element coupled between said first and second outputs;
- said output impedance a function of the ratio of the current drive of the first and second outputs and the value of said series resistance element;
- and
- the voltage on said second output being a function of said interface and the current input to said internal amplifier.
A line driver for driving a transmission line having a line impedance associated therewith, comprising:
- an internal amplifier having an output, and a non-inverting current input;
- a first stage of amplification for driving a first output, said first output coupled to said non-inverting current input through an interface, said first stage of amplification driven by said internal amplifier;
- a second stage of amplification for driving a second output to provide an output signal to the transmission line with an associated output impedance, said second stage of amplification a replica stage of said first stage of amplification and driven by said internal amplifier;
- a series resistance element coupled between said first and second outputs;
- said output impedance a function of the ratio of the current drive of the first and second stages of amplification to said non-inverting input and the value of said series resistance element;
- and
- a calibration engine for determining the value of said ratio required to change the value of said output impedance to substantially equal the line impedance and varying the parameters of at least one of said first and second stages of amplification to change said ratio to the determined ratio.
A method for amplifying an input signal in an integrated circuit, comprising:
- coupling a first output of an internal amplifier to a non-inverting input thereof through an interface;
- coupling a second output of the internal amplifier through a series resistance element to the first output to provide an output signal from the integrated circuit with an associated output impedance;
- the output impedance a function of the ratio of the current drive of the first and second outputs and the value of the series resistance element;
- and
- the voltage on the second output being a function of the interface and the current input to the internal amplifier.
A method for driving a transmission line having a line impedance associated therewith, comprising the steps of:
- providing an internal amplifier having an output, and a non-inverting current input;
- driving a first output with a first stage of amplification, the first output coupled to the non-inverting current input through an interface, the first stage of amplification driven by the internal amplifier;
- driving a second output with a second stage of amplification to provide an output signal to the transmission line with an associated output impedance, the second stage of amplification a replica stage of the first stage of amplification and driven by the internal amplifier;
- coupling the first and second outputs with a series resistance element disposed therebetween;
- the output impedance a function of the ratio of the current drive of the first and second stages of amplification to the non-inverting input and the value of the series resistance element;
- and
- determining with a calibration engine the value of the ratio required to change the value of the output impedance to substantially equal the line impedance and varying the parameters of at least one of the first and second stages of amplification to change the ratio to the determined ratio.
A calibration system for calibrating the output impedance of a line driver to match the impedance of a transmission line, which line driver has an internal amplifier with a first output at a first gain fed back to the input thereof through an interface device and a second output with a second gain that is a replica of the first gain with a series resistance element connected between the first and second outputs, and wherein the output impedance of the line driver is a function of the ratio of the current drive at the first and second outputs, comprising:
- a calibration device for determining as a calibration value the ratio of the current drive at the first and second outputs that will provide an output impedance from the line driver that will substantially match the transmission line impedance;
- and
- means for varying the ratio of the current drive at the first and second outputs in accordance with the calibration value.
Dependencies are inferred from the claim text.