AnSem - Innovation on chip

PCI-Express SerDes

PCI-Express SerDes
PCI-Express SerDes

The real world problem

PCI Express (PCIe) is a computer standard designed to replace the older PCI, PCI-X and AGP bus standards. PCIe has a number of improvements over previous bus standards including:

  • higher bus throughput
  • lower I/O pin count
  • smaller physical footprint

PCI Express is used in consumer, server, and industrial applications, as a motherboard-level interconnect (to link motherboard-mounted peripherals), a passive backplane interconnect and as an expansion card interface for add-in boards.

In virtually all modern PCs, from consumer laptops and desktops to enterprise data servers, the PCIe bus serves as the primary motherboard-level interconnect, connecting the host system processor with both integrated-peripherals (surface mounted ICs) and add-on peripherals (expansion cards.).

In the consumer space, time to market is everything.  Our customer, designing on TSMC's 90nm process, needed a PCIe SerDes to complete the functionality of their device.  To maximize access to their emerging market they needed a rapid, right first time design.

The solution

Utilising previous silicon proven experience with much more technically challenging state-of-the-art SerDes applications like SONET, AnSem was able to complete this development in a short time allowing our customer to quickly gain access to the market without missing their window-of-opportunity.

Our modular IP contains two separate macros which allow the customer to make silicon efficient multi-lane PCIe interfaces if required. Furthermore, the IP contains a number of assets to increase the overall flexibility:

  • Serial loopback between RX and TX modules to allow easy testing
  • Selectable TX de-emphasis to compensate high-frequency channel losses
  • Programmable current settings in critical sub-circuits to allow performance optimization

Key technical statistics

  • 2.5Gbps datarate
  • Limited area of 690µm by 780µm (including pads and line receiver/driver)
  • Low power consumption of less than 80mW  (including line driver)