Impedance controlled transmitter with adaptive compensation for chip-to-chip communication

1. A transmission apparatus, comprising:

a transmitter circuit arranged to transmit a signal having a frequency characteristic, wherein the transmitter circuit comprises a driver circuit and a filter;

a replica driver circuit operatively connected to the transmitter circuit arranged to adjust the driver circuit, wherein the replica driver circuit further comprises:

a buffer arranged to output a reference voltage potential,

a comparator arranged to generate an output signal dependent on a difference between the reference voltage potential and a desired reference voltage potential, and

a state machine arranged to adjust the buffer dependent on the output from the comparator, and

a voltage control circuit operatively connected to the transmitter circuit arranged to adjust the filter, wherein adjustments to any one of the driver circuit and the filter adjust the frequency characteristic of the signal.

2. The transmission apparatus of claim 1 , further comprising:

a precision resistor operatively connected to the buffer.

3. The transmission apparatus of claim 1 , the filter comprising at least one delay element operatively connected to the voltage control circuit, wherein the voltage control circuit is arranged to adjust the at least one delay element.

4. The transmission apparatus of claim 1 , the filter comprising at least one delay element arranged to receive a filter code.

5. The transmission apparatus of claim 4 , wherein the filter code comprises a finite impulse response filter code.

6. The transmission apparatus of claim 4 , wherein the filter code is dependent on an eye pattern of the signal.

7. The transmission apparatus of claim 4 , the at least one delay element comprising:

a first delay line arranged to delay an input dependent on a control voltage signal; and

a second delay line arranged to delay the input dependent on the control voltage signal, wherein a delay of the first delay line and a delay of the second delay line are each independent on the filter code.

8. The transmission apparatus of claim 1 , wherein the driver circuit comprises a pull-up driver circuit.

9. The transmission apparatus of claim 1 , wherein the driver circuit comprises a pull-down driver circuit.

10. The transmission apparatus of claim 1 , the voltage control circuit comprising:

a delay line arranged to generate a delayed reference clock signal dependent on a reference clock signal; and

a phase detector arranged to generate a control voltage signal dependent on a phase difference between the reference clock signal and the delayed reference clock signal, wherein the control voltage signal adjusts the delay line.

11. A method for transmitting data, comprising:

transmitting a signal having a frequency characteristic; and

equalizing the transmitting, wherein the equalizing comprises:

adjusting a drive strength of the signal, wherein adjusting drive strength comprises:

outputting from a buffer a reference voltage potential,

comparing the reference voltage potential and a desired reference voltage potential, and

adjusting the outputting dependent on the comparing, and

adjusting a delay of the signal, wherein the adjusting the delay comprises:

generating a control voltage for a delay element dependent on a phase difference between a reference clock signal and a delayed reference clock signal, and

selecting between a plurality of delay lines using a filter code dependent on an eye pattern of the signal.

12. The method of claim 11 , wherein adjusting the drive strength of the signal comprises adjusting a pull-up circuit.

13. The method of claim 11 , wherein adjusting the drive strength of the signal comprises adjusting a pull-down circuit.