In an embodiment, an apparatus includes a first integrated circuit (IC) chip configured to receive a timing signal and a reference clock signal; and a second IC chip configured to receive the timing signal and the reference clock signal. The first and second IC chips are configured to generate respective first and second reference time signals based on the timing signal and the reference clock signal. The first and second IC chips include a respective first phase lock loop (PLL) and second PLL. The first PLL and the second PLL are synchronized to each other based on the first reference time signal and the second reference time signal.