Method and apparatus to linearize output buffer and on-chip termination
View Patent ↗A driver circuit that outputs a data signal uses feedback of the data signal to the driver circuit to modulate a drive strength of the driver circuit. The driver circuit has a pull-up driver stage and a pull-down driver stage. The pull-up driver stage uses a pull-up control circuit to modulate a drive strength of the pull-up driver stage dependent on a voltage of the data signal. The pull-down driver stage uses a pull-down control circuit to modulate a drive strength of the pull-down driver stage dependent on the voltage of the data signal.
1. A communication system, comprising:
a pull-up driver portion arranged to generate a first transition on a data signal, the pull-up driver portion comprising:
at least one pull-up device operatively connected to the data signal, and pull-up control circuitry arranged to modulate a drive strength of the pull-up device dependent on a feedback of the data signal to the pull-up control circuitry; and
a pull-down driver portion arranged to generate a second transition on the data signal, the pull-down driver portion comprising:
at least one pull-down device operatively connected to the data signal, and
pull-down control circuitry arranged to modulate a drive strength of the pull-down device dependent on a feedback of the data signal to the pull-down control circuitry,
wherein at least one of:
the pull-up control circuitry is arranged to form a voltage potential divider at an input to the pull-up device dependent on the first transition; and
the pull-down control circuitry is arranged to form a voltage potential divider at an input to the pull-down device dependent on the second transition.
2. The communication system of claim 1 , wherein the pull-up driver portion and the pull-down driver portion are arranged to receive input data.
3. The communication system of claim 1 , wherein the first transition is a low to high transition.
4. The communication system of claim 1 , wherein the second transition is a high to low transition.
5. The communication system of claim 1 , further comprising a data channel arranged to propagate the data signal to a receiver circuit.
6. A communication system, comprising:
a pull-up driver portion arranged to generate a first transition on a data signal, the pull-up driver portion comprising:
at least one pull-up device operatively connected to the data signal, and
pull-up control circuitry arranged to modulate a drive strength of the pull-up device dependent on a feedback of the data signal to the pull-up control circuitry; and
a pull-down driver portion arranged to generate a second transition on the data signal, the pull-down driver portion comprising:
at least one pull-down device operatively connected to the data signal, and
pull-down control circuitry arranged to modulate a drive strength of the pull-down device dependent on a feedback of the data signal to the pull-down control circuitry,
wherein at least one of:
the pull-up driver portion further comprises a diode-connected pull-up device arranged to compensate for current through the pull-up device during a portion of the first transition; and
the pull-down driver portion further comprises a diode-connected pull-down device arranged to compensate for current through the pull-down device during a portion of the second transition.
7. A method for handling a data signal, comprising:
receiving data;
establishing a voltage divider potential dependent on the data signal and the data;
when the data represents a logic high, pulling up a voltage of the data signal, wherein the pulling up comprises:
feeding back the data signal, and
modulating the pulling up dependent on the feeding back; and
when the data represents a logic low, pulling down the voltage of the data signal, wherein the pulling down comprises:
feeding back the data signal, and
modulating the pulling down dependent on the feeding back.
8. The method of claim 7 , wherein the pulling up further comprises supplementarily sourcing current to the data signal dependent on a voltage of the data signal.
9. The method of claim 7 , wherein the pulling down further comprises supplementarily sinking current from the data signal dependent on a voltage of the data signal.
10. The method of claim 7 , further comprising:
propagating the data signal; and
receiving the data signal.
11. The method of claim 7 , wherein the modulating the pulling up is also dependent on the voltage divider potential.
12. The method of claim 7 , wherein the modulating the pulling down is also dependent on the voltage divider potential.
13. A communication system, comprising:
means for receiving input data;
means for pulling up a voltage of a data signal when the input data is a logic high, wherein the means for pulling up comprises:
first control means for controlling a drive strength of the means for pulling up dependent on a feedback of the data signal to the first control means; and
means for pulling down the voltage of the data signal when the input data is a logic low, wherein the means for pulling down comprises:
second control means for controlling a drive strength of the means for pulling down dependent on a feedback of the data signal to the second control means.
where in at least one of:
the first control means comprises means for establishing a voltage divider potential dependent on the data signal and the input data, wherein the drive strength of the means for pulling up is dependent on the voltage divider potential; and
the second control means comprises means for establishing a voltage divider potential dependent on the data signal and the input data, wherein the drive strength of the means for pulling down is dependent on the voltage divider potential.