Differential-to-LVDS/0.7V Differential PCI Express Jitter Attenuator

The 8741004 is a high performance Differential-to-LVDS/0.7V Differential Jitter Attenuator designed for use in PCI Express® systems. In some PCI Express systems, such as those found in desktop PCs, the PCI Express clocks are generated from a low bandwidth, high phase noise PLL frequency synthesizer. In these systems, a jitter attenuator may be required to attenuate high frequency random and deterministic jitter components from the PLL synthesizer and from the system board. The 8741004 has 3 PLL bandwidth modes: 200kHz, 600kHz and 2MHz. The 200kHz mode will provide maximum jitter attenuation, but with higher PLL tracking skew and spread spectrum modulation from the motherboard synthesizer may be attenuated. The 600kHz provides an intermediate bandwidth that can easily track triangular spread profiles, while providing good jitter attenuation. The 2MHz bandwidth provides the best tracking skew and will pass most spread profiles, but the jitter attenuation will not be as good as the lower bandwidth modes. Because some 2.5Gb serdes have x20 multipliers while others have x25 multipliers, the 8741004 can be set for 1:1 mode or 5/4 multiplication mode (i.e. 100MHz input/125MHz output) using the FSEL pins. The 8741004 uses our 3rd Generation FemtoClock® PLL technology to achieve the lowest possible phase noise. The device is packaged in a 24 Lead TSSOP package, making it ideal for use in space constrained applications such as PCI Express add-in cards.