Family of Jitter atteunation clocks from Silicon Laboratories with a simplified design of coherent optical line cards and modules. This Si534xH Will be a coherent optical clock family reducing the discrete timing over large footprint voltages seen under the oscillators. The Si5344H and Si5342H clocks combine frequency flexibility with jitter performance of 50fs RMS. With a jitter attenuating PLL, high-frequency output drivers.