Methods and apparatus for accurate transmitter simulation for link optimization

1. An apparatus for generating a data output signal, the apparatus comprising:

a pre-emphasis filter that receives an input data signal and outputs a pre-emphasized signal;

an edge-shape filter that receives the pre-emphasized signal and outputs an edge-shaped signal, wherein the edge-shape filter includes

a non-linearity correction stage that applies a non-linearity correction to the pre-emphasized signal and outputs a non-linearity-corrected signal, and

a linear filter that applies linear filtering to the non-linearity-corrected signal and outputs the edge-shaped signal; and

a driver that receives the edge-shaped signal and generates the data output signal.

2. The apparatus of claim 1 , wherein a pre-emphasis setting signal is provided to the pre-emphasis filter and the non-linearity correction filter, and

wherein the non-linearity correction stage applies a pre-emphasis-dependent correction that depends on the pre-emphasis setting signal.

3. The apparatus of claim 1 , wherein the non-linearity correction stage applies a correction to the pre-emphasized signal that depends on a soak time of the input data signal.

4. The apparatus of claim 1 , wherein the non-linearity correction stage applies a correction to introduce asymmetry between rise time and fall time in the pre-emphasized signal.

5. The apparatus of claim 1 , wherein a data rate is input as a parameter to the non-linearity correction filter.

6. The apparatus of claim 1 , wherein a voltage output differential parameter is input as a parameter to the pre-emphasis filter, the edge-shape filter, and the driver.

7. The apparatus of claim 1 , further comprising:

stored tap coefficients of the pre-emphasis filter, wherein the tap coefficients are determined using a fitting procedure.

8. The apparatus of claim 7 , wherein the stored tap coefficients correspond to tap coefficients for base single-bit response waveforms shifted by −1, 0, +1 and +2 unit times.

9. The apparatus of claim 7 , wherein the fitting procedure fits a first waveform to a second waveform, wherein the first waveform comprises a summation of products of the tap coefficients and time-shifted base single-bit response waveforms, and wherein the second waveform comprises a measured single-bit response waveform.

10. The apparatus of claim 9 , wherein the fitting procedure minimizes a mean square error between the first and second waveforms.

11. The apparatus of claim 9 , wherein the time-shifted base single-bit response waveforms are generated without pre-emphasis applied, and wherein the measured single-bit response waveform is generated with pre-emphasis applied.

12. The apparatus of claim 9 , wherein said single-bit response waveforms are generated using pseudo-random binary sequences.

13. A method for generating a data output signal, the method comprising:

receiving an input data signal by a pre-emphasis filter;

outputting a pre-emphasized signal by the pre-emphasis filter;

receiving the pre-emphasized signal by an edge-shape filter;

applying a non-linearity correction to the pre-emphasized signal by a non-linearity correction stage of the edge-shape filter to generate a non-linearity-corrected signal;

applying a linear filtering to the non-linearity-corrected signal by a linear filter of the edge-shape filter to generate an edge-shaped signal;

outputting the edge-shaped signal by the edge-shape filter;

receiving the edge-shaped signal by a driver; and

generating the data output signal by the driver.

14. The method of claim 13 , further comprising:

providing a pre-emphasis setting signal to the pre-emphasis filter and the non-linearity correction filter; and

applying, by the non-linearity correction stage, a pre-emphasis-dependent correction that depends on the pre-emphasis setting signal.

15. The method of claim 13 , further comprising:

applying, by the non-linearity correction stage, a correction to the pre-emphasized signal that depends on a soak time of the input data signal.

16. The method of claim 13 , further comprising:

applying, by the non-linearity correction stage, a correction to introduce asymmetry between rise time and fall time in the pre-emphasized signal.

17. The method of claim 13 , further comprising:

inputting a data rate as a parameter to the non-linearity correction filter; and

inputting a voltage output differential parameter as a parameter to the pre-emphasis filter, the edge-shape filter, and the driver.

18. The method of claim 13 , further comprising:

determining tap coefficients of the pre-emphasis filter using a fitting procedure; and

storing the tap coefficients,

wherein the tap coefficients correspond to tap coefficients for base single-bit response waveforms shifted by −1, 0, +1 and +2 unit times.

19. The method of claim 18 , further comprising:

fitting a first waveform to a second waveform by the fitting procedure, wherein the first waveform comprises a summation of products of the tap coefficients and time-shifted base single-bit response waveforms, and wherein the second waveform comprises a measured single-bit response waveform.

20. The method of claim 19 , wherein the time-shifted base single-bit response waveforms are generated without pre-emphasis applied, and wherein the measured single-bit response waveform is generated with pre-emphasis applied.

21. The method of claim 20 , wherein said single-bit response waveforms are generated using pseudo-random binary sequences.