Getting the most out of a RF signal chain design partly depends on providing a low phase noise, clean clock to the A/D converter. In this application report, phase noise data taken using the Texas Instruments’ LMX1204 clock distribution device is studied. In general, the phase noise performance of any clock distribution method, is not only dependent upon the phase noise of the input clock source, but also the active clock signal chain as well. In this case the LMX1204 will be studied in both single and cascaded configurations. In general, the performance measurements confirm the operational ability of the LMX1204 device to provide as an adequate distribution method, up to 16 channels, with minimal degradation in converter performance.
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When numerous devices in a system require a shared clock source, distributing the clock signal inadequately leads to degradation in system performance. This becomes a prevalent concern for applications utilizing digital beamforming (phased array radar, communications, ultrasound) as signal distortion increases directly as a result of increased clock jitter. The LMX1204 is a clock distribution device designed for applications requiring minimal added phase noise within the frequency range 300 MHz to 12.8 GHz. Although the LMX1204 is a high-speed clock distribution device allowing for buffered, multiplied, and divided output frequency (relative to the input frequency), this report will focus solely on the performance of this device in a buffered (1-to-1) configuration.