Maxim IC MAX14950 PCI Express 3.0 Equalizer
Assume that you have a very long trace of differential PCIs microstrip, using the 5 GT/s PCI Express 2.0 or the latest 8 GT/s PCI Express 3.0 on your PCB. With the long trace length, you are likely to see signal degradation due to the skin effect, Intel Symbol Interference or the signal path discontinuity by the time the signal reaches the receiver.
The degradation in the signal is especially marked for the PCI Express 3.0 at 8.0 GT/sec. Maxim-IC provides a solution for the maintaining the Signal Integrity using its MAX14950 IC. MAX14950 is available in 42 pin TQFN package and contains quad PCIe equalizers. While the MAX14950 is more likely to be used for the PCI Express 2.0 ( 5 GT/sec) and PCI Express 3.0 ( 8 GT/s), it is backward compatible with the earlier PCI Express 1.0 ( 2.5 GT/sec).
The Maxim IC MAX14950 is typically used at transmitter as well as the receiver end. There are two types of controls available at the Maxim IC MAX14950 – one if the chip is place right at next to the transmitter and another if the chip is placed just before the receiver. The INEQ1 and INEQ0 pics control the Input Equalization and the Pins OEQ2, OEQ1, OEQ0 are used for preshoot. The amount of the input equalization or the outout preshoot is programmable depending upon the amount of equalization.
If you are concerned about the channel loss and eye closing, the Maxim IC MAX14950 is something you would like to consider in your design. You may experiment with the different settings of the INEQ1 and INEQ0 at the receiver and and with OEQ2, OEQ1, OEQ0 at the transmitter end to see which one gets you better result. Using the Maxim IC MAX14950, you can typically extend the range to 20 inch of length on the PCB.