Device with pre-emphasis based transmission

• US 8,605,759 B1
• Filed: 11/13/2012
• Issued: 12/10/2013
• Est. Priority Date: 10/22/2002
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Wu, Lei, Hu, Timothy
• Primary Examiner(s): Qureshi, Afsar M
• Application Number:
  US13/675,577
• Time in Patent Office: 392 Days
• Field of Search: 370/395.62, 370/532, 370/534, 370/535, 370/539, 710/5, 710/22, 710/300, 710/305, 341/100, 341/101, 711114-168, 375/259, 375/295, 375/354
• US Class Current: 370/535
• CPC Class Codes: G06F 13/4072 Drivers or receivers G06F13/4086 takes precedence; for multistate logic circuits H03K19/0002
• CPC Class Codes: H04L 25/0292 Arrangements specific to the receiver end
• CPC Class Codes: H04L 25/03025 using a two-tap delay line

Abstract

A device is provided and includes a multiplexer that receives signals and generates an output signal based on a selected one of the signals. The output signal includes frequencies and has a respective signal magnitude at each of the frequencies. A control circuit determines gain values. A transmitter provides pre-emphasis to the output signal to offset a characteristic of a channel, and transmits the output signal with the pre-emphasis on the channel. The transmitter, in providing the pre-emphasis: provides delayed versions of the output signal, where each of the delayed versions of the output signal has a different amount of delay than other delayed versions of the output signal; and amplifies each of the delayed versions of the output signal based on a respective one of the gain values such that certain ones of the signal magnitudes are amplified, and other ones of the signal magnitudes are attenuated.

Claims

1. A device comprising:

a multiplexer configured to (i) receive a plurality of signals, and (ii) generate an output signal based on a selected one of the plurality of signals, wherein the output signal comprises a plurality of frequencies and has a respective signal magnitude at each of the plurality of frequencies;

a control circuit configured to determine a plurality of gain values; and

a transmitter configured to (i) provide pre-emphasis to the output signal to offset a characteristic of a channel, and (ii) transmit the output signal with the pre-emphasis on the channel,

wherein the transmitter, in providing the pre-emphasis to the output signal, is configured to

provide a plurality of delayed versions of the output signal, wherein each of the delayed versions of the output signal has a different amount of delay than other ones of the delayed versions of the output signal, and

amplify each of the delayed versions of the output signal based on a respective one of the plurality of gain values such that (i) the signal magnitudes at certain ones of the plurality of frequencies are amplified, and (ii) the signal magnitudes at other ones of the plurality of frequencies are attenuated.

2. The device of claim 1, wherein the control circuit is configured to determine the plurality of gain values such that (i) the signal magnitudes at the certain ones of the plurality of frequencies are amplified, and (ii) the signal magnitudes at the other ones of the plurality of frequencies are attenuated.

3. The device of claim 1, wherein the characteristic of the channel includes frequency dependent noise.

4. The transmitter of claim 1, wherein the control circuit is preprogrammed based on at least (i) data stored in memory, or (ii) data input to a physical layer of the transmitter.

5. The device of claim 1, wherein the transmitter comprises:

an analog front end configured to receive the output signal generated by the multiplexer,

wherein the control circuit is configured to determine the plurality of gain values including

based on the characteristic of the channel, generating a first gain value and a second gain value;

a first amplifier configured to, based on the first gain value, amplify the output signal to generate a first amplified signal;

a first delay device configured to delay the output signal to generate a first delayed signal;

a second amplifier configured to, based on the second gain value, amplify the first delayed signal to generate a second amplified signal; and

a summer configured to sum the first amplified signal and the second amplified signal to generate the output signal with the pre-emphasis.

6. The transmitter of claim 5, wherein the control circuit is configured to, based on the characteristic of the channel, generate the second gain value to be different than the first gain value to emphasize the output signal generated by the multiplexer differently than the first delayed signal.

7. The transmitter of claim 5, wherein the control circuit is configured to select the second gain value to be different than the first gain value to adjust a first magnitude of a first frequency of the output signal generated by the multiplexer differently than a second magnitude of a second frequency of the output signal generated by the multiplexer.

8. The transmitter of claim 5, wherein:

the control circuit is configured to generate a third gain value based on the characteristic of the channel;

the transmitter further comprises;

a second delay device configured to delay the first delay signal to generate a second delayed signal, and

a third amplifier configured to amplify the second delayed signal to generate a third amplified signal based on the third gain value; and

the at least one summer is configured to sum the first amplified signal, the second amplified signal and the third amplified signal to generate the output signal with the pre-emphasis.

9. The transmitter of claim 8, wherein at least one of the first delay device or the second delay device provides a unit delay.

10. The transmitter of claim 8, wherein at least the first delay device or the second delay device provides a partial unit delay.

11. The transmitter of claim 8, wherein:

the control circuit is configured to generate a fourth gain value based on the characteristic of the channel;

the transmitter further comprises

a third delay device configured to delay the second delay signal to generate a third delayed signal, and

a fourth amplifier configured to amplify the third delayed signal to generate a fourth amplified signal based on the fourth gain value; and

the summer is configured to sum the first amplified signal, the second amplified signal, the third amplified signal, and the fourth amplified signal to generate the output signal with the pre-emphasis.

12. The transmitter of claim 5, wherein:

the first amplifier includes a first differential input and a first differential output, wherein the first differential input receives the output signal generated by the multiplexer, and wherein the first differential output outputs the first amplified signal; and

the second amplifier includes a second differential input and a second differential output, wherein the second differential input receives the first delayed signal, and wherein the second differential output outputs the second amplified signal.

13. A method comprising:

receiving a plurality of signals;

generating an output signal via a multiplexer based on a selected one of the plurality of signals, wherein the output signal comprises a plurality of frequencies and has a respective signal magnitude at each of the plurality of frequencies;

determining a plurality of gain values;

providing pre-emphasis to the output signal to offset a characteristic of a channel; and

transmitting the output signal with the pre-emphasis on the channel,

wherein the providing of the pre-emphasis to the output signal comprises

providing a plurality of delayed versions of the output signal, wherein each of the delayed versions of the output signal has a different amount of delay than other ones of the delayed versions of the output signal, and

amplifying each of the delayed versions of the output signal based on a respective one of the plurality of gain values such that (i) the signal magnitudes at certain ones of the plurality of frequencies are amplified, and (ii) the signal magnitudes at other ones of the plurality of frequencies are attenuated.

14. The method of claim 13, further comprising determining the plurality of gain values such that (i) the signal magnitudes at the certain ones of the plurality of frequencies are amplified, and (ii) the signal magnitudes at the other ones of the plurality of frequencies are attenuated.

15. The method of claim 13, further comprising:

receiving the output signal generated by the multiplexer;

based on the characteristic of the channel, generating a first gain value and a second gain value;

based on the first gain value, amplifying the output signal to generate a first amplified signal;

delaying the output signal to generate a first delayed signal;

based on the second gain value, amplifying the first delayed signal to generate a second amplified signal; and

summing the first amplified signal and the second amplified signal to generate the output signal with the pre-emphasis.

16. The method of claim 15, further comprising, based on the characteristic of the channel, generating the second gain value to be different than the first gain value to emphasize the output signal generated by the multiplexer differently than the first delayed signal.

17. The method of claim 15, further comprising selecting the second gain value to be different than the first gain value to adjust a first magnitude of a first frequency of the output signal generated by the multiplexer differently than a second magnitude of a second frequency of the output signal generated by the multiplexer.

18. The method of claim 15, further comprising:

generating a third gain value based on the characteristic of the channel;

delaying the first delay signal to generate a second delayed signal;

amplifying the second delayed signal to generate a third amplified signal based on the third gain value; and

summing the first amplified signal, the second amplified signal and the third amplified signal to generate the output signal with the pre-emphasis.

19. The method of claim 18, further comprising:

generating a fourth gain value based on the characteristic of the channel;

delaying the second delay signal to generate a third delayed signal;

amplifying the third delayed signal to generate a fourth amplified signal based on the fourth gain value; and

summing the first amplified signal, the second amplified signal, the third amplified signal, and the fourth amplified signal to generate the output signal with the pre-emphasis.

20. The method of claim 15, further comprising:

receiving the output signal generated by the multiplexer via a first differential input of a first amplifier;

outputting the first amplified signal via a first differential output of the first amplifier;

receiving the first delayed signal via a second differential input of a second amplifier; and

outputting the second amplified signal via a second differential output of the second amplifier.