Voltage-mode transmitter driver

1. A transmitter driver circuit for transmitting a digital output signal, comprising:

a main driver for driving transmission of the digital output signal across a communication channel based on a received digital input signal;

an equalization driver arranged in parallel with the main driver, comprising a variable-resistance path for:

receiving the digital input signal; and

providing pre-emphasis to the digital output signal to increase the peak-to-peak amplitude of the digital output signal by, in response to changes in the amplitude of the digital input signal, reducing the resistance of the variable-resistance path for a predetermined period of time.

2. The transmitter driver circuit of claim 1 wherein the main driver operates in voltage mode and the digital output signal is a voltage-mode digital signal.

3. The transmitter driver circuit of claim 1 wherein the main driver operates in current mode and the digital output signal is a current-mode digital signal.

4. The transmitter driver circuit of claim 1 , wherein the equalization driver further comprises a finite impulse response (FIR) equalization circuit for providing FIR equalization to the digital output signal based on the data input signal.

5. The transmitter driver circuit of claim 4 , wherein the FIR equalization circuit further comprises one or more tap delays for generating one or more delayed input signals.

6. The transmitter driver circuit of claim 5 , wherein the one or more tap delays comprise a plurality of tap delays and the one or more delayed input signals comprise a plurality of delayed input signals.

7. The transmitter driver circuit of claim 5 , wherein:

the one or more tap delays comprises a variable tap delay having a variable delay duration; and

the one or more delayed signals comprises a delayed input signal having a variable delay relative to the digital input signal based on the variable delay duration of the variable tap delay.

8. The transmitter driver circuit of claim 7 , wherein the equalization driver varies the duration of the predefined period of time based on the variable delay of the delayed input signal.

9. The transmitter driver circuit of claim 1 , wherein:

the equalization driver provides equalization to the digital output signal based on a first data signal and a second data signal, the first data signal and the second data signal each having a disabling value and an enabling value;

the variable-resistance path switches between a baseline resistance in response to disabling values of the first and second signals and a low resistance in response to an enabling value of the first or second signal; and

the equalization driver further comprises a power source for:

providing positive polarity signal gain to the digital output signal via the variable-resistance path in response to an enabling value of the first signal; and

providing negative polarity signal gain to the digital output signal via the variable-resistance path in response to an enabling value of the second signal.

10. The transmitter driver circuit of claim 9 wherein the gain provided is voltage-mode gain.

11. A method for equalizing an output signal, comprising:

detecting an input data signal;

generating a delayed version of the input data signal; and

in response to detecting that a value of the input data signal has changed relative to the delayed version,

enabling a low-resistance path;

providing pre-emphasis to the output signal via the low-resistance path to increase the peak-to-peak amplitude of the output signal for a predetermined duration; and

at the end of the predetermined duration, disabling the low-resistance path and disabling pre-emphasis.

12. The method of claim 11 , wherein the pre-emphasis is voltage-mode pre-emphasis.

13. The method of claim 11 , wherein the duration is one unit interval of the input data signal.

14. The method of claim 11 , wherein the step of providing pre-emphasis comprises:

if the value of the input data signal has increased relative to the delayed version, providing positive-polarity pre-emphasis; and

if the value of the input data signal has decreased relative to the delayed version, providing negative-polarity pre-emphasis.

15. The method of claim 11 , wherein the step of generating a delayed version comprises introducing 1 unit interval of delay to the input data signal.

16. The method of claim 11 , wherein the step of generating a delayed version comprises introducing a variable amount of delay to the input data signal.

17. An equalization driver for providing equalization to an output signal based on a first data signal and a second data signal, the first data signal and the second data signal each having a disabling value and an enabling value, comprising:

a variable-resistance path for switching between a baseline resistance in response to disabling values of the first and second signals and a low resistance in response to an enabling value of the first or second signal; and

a power source for:

providing positive polarity signal gain to the output signal via the variable-resistance path in response to an enabling value of the first signal; and

providing negative polarity signal gain to the output signal via the variable-resistance path in response to an enabling value of the second signal.

18. The equalization driver of claim 17 wherein the gain provided is voltage-mode gain.