Si53212/Si53208/Si53204 PCIe Clock Buffers Skyworks Solutions Inc. Si53212/Si53208/Si53204 PCIe Clock Buffers are high-performance, low-additive jitter, low-power PCIe clock fanout buffers. The devices can source 12, 8, or 4 100MHz PCIe clock outputs. All differential clock outputs comply with PCIe Gen1/2/3/4 common clock and separate reference clock specifications.