Optimal equalization partitioning
An optical module configured to electrically connect to a host. A linear equalizer performs equalization on a host equalized signal to create a module equalized signal, and a driver configured to present the module equalized signal from the linear equalizer to an optical conversion device at a magnitude suitable for the optical conversion device. An optical conversion device receives the module equalized signal from the driver, converts the module equalized signal to an optical signal, and transmit the optical signal over an optical channel. Also part of the optical module is an interface which communicates supplemental equalizer settings to the host. A memory stores the supplemental equalizer settings which reflect the optical modules effect on a signal passing through the optical module. A controller oversees communication of the supplemental equalizer settings to the host such that the host uses the supplemental equalizer settings to modify host equalizer settings.
1. A host configured to electrically connect to a linear module, the host comprising:
a host input configured to connect to a low-speed communication channel;
a low-speed host-to-linear module interface configured to communicate with the linear module, and receive and process equalizer settings received over the low-speed communication channel from the linear module;
an equalizer configured to perform equalization on an outgoing signal to create an equalized outgoing signal, using the equalizer settings provided from the linear module, prior to the outgoing signal being transmitted from the host to the linear module;
a driver configured to transmit the equalized outgoing signal from the host to the linear module; and
an output connected to the driver configured to transmit the equalized outgoing signal, as an electrical signal, from the host to the linear module over a data channel.
2. The host of claim 1 wherein the linear module included an optic module configured to convert an electrical signal to an optical signal and transmit the electrical signal over a channel.
3. The host of claim 1 wherein the equalization equalizes the equalized outgoing signal to compensate for the signal path from the host to an output of the linear module.
4. The host of claim 1 wherein the equalizer in the host comprises a linear feed-forward equalizer which pre-compensates the equalized outgoing signal for effects of passing from the host to an output of the linear module.
5. The host of claim 1 wherein the low-speed interface comprises an I2C interface or a SPI type interface.
6. The host of claim 1 wherein the equalizer in the host is a nonlinear equalizer having nonlinear equalizer settings that predistort the outgoing signal to counteract the unwanted effects of the host and the linear module.
7. The host of claim 1 wherein the linear module comprises:
a linear equalizer configured to perform linear equalization on the equalized outgoing signal to create the equalized outgoing signal;
a driver configured to receive and amplify the equalized outgoing signal;
an electrical to optical device configured to convert the equalized outgoing signal from the driver to an optical signal, and transmit the optical signal over a fiber optic cable;
a memory configured to store supplemental FFE or other pre-distortion settings;
a low-speed interface configured to communicate with the host; and
a controller configured to control communication over the low-speed interface and communicate with the memory to communicate the supplemental FFE settings to the host.
8. The host of claim 6 wherein the nonlinear equalizer settings of the host are selected to modify host pre-distortion settings to force the pre-distortion processing to also account for the linear module.
9. The host of claim 6 wherein the nonlinear equalizer settings in the host are calculated during a training process and stored in a memory located in the linear module.
10. A method for configuring an equalizer located in a host and processing an outgoing data signal prior to transmission, of the outgoing data signal, to a linear module:
receiving at the host, over a low-speed channel, from the linear module, supplemental equalizer settings;
processing the supplemental equalizer settings with a low-speed interface in the host, the host receiving the supplemental equalizer settings over the low-speed channel from the linear module;
modifying equalizer settings for the equalizer located in the host, based on the supplemental equalizer settings to create updated equalizer settings;
prior to transmission over a data channel, receiving and processing the outgoing data signal with the equalizer located in the host using the updated equalizer settings to create a host processed outgoing signal, wherein the host processed outgoing signal includes pre-distortion to counter the effects of the signal path through the linear module; and
transmitting the host processed outgoing signal to the linear module.
11. The method of claim 10 wherein the linear module transmits an optical signal over an optical channel.
12. The method of claim 10 wherein processing the outgoing data signal with the equalizer in the host includes linear and non-linear equalization.
13. The method of claim 10 further comprising generating the supplemental equalizer settings during a testing phase or a training phase.
14. The method of claim 10 , wherein the low-speed interface comprises an I2C interface or a SPI type interface.
15. A host configured to process a signal to be transmitted to an optic module, the host comprising:
an optic module configured to generate supplemental equalizer settings, the optic module comprising:
an equalizer configured to perform non-linear equalization;
a controlled configured to generate the supplemental equalizer settings;
optic module-to-host interface configured to transmit the supplemental equalizer settings from the optic module to the host over the low-speed channel;
a host-to-optic module interface configured to receive and process the supplemental equalizer settings over a low-speed communication channel from the optic module;
a host driver with an equalizer configured to:
update the equalizer with the supplemental equalizer settings received by the host-to-optic module interface;
equalize an outgoing signal with the equalizer based, at least in part, on the supplement equalizer settings to create an equalized signal; and
drive the equalized signal over an electrical channel to the optic module.
16. The host of claim 15 wherein the optic module performs only linear equalization and the host performs non-linear equalization.
17. The host of claim 15 wherein the equalization by the host equalizes the outgoing signal to compensate for the signal path from the host to an optical output of the optic module.
18. The host of claim 15 wherein low-speed communication channel comprises an I2C channel or a SPI type channel.