SNAA366 October 2022 LMX1204
The LMX1204 is a high-performance clock distribution device. This device is intended to distribute a low phase-noise clock or local oscillator (LO) signal across many channels. The device also employs an integrated multiplier operating between 3.2- and 6.4-GHz output. Designers can use the multiplier feature to create a high-frequency signal from a low-frequency reference source and then distribute as needed. This approach eliminates the need for a separate radio-frequency (RF) synthesizer to generate the signal and the additional power dissipation of such a device. This note presents the phase-noise performance of the multiplier feature in the LMX1204 compared to industry test equipment to gauge the relative performance of the LMX1204. The final test uses the multiplied-up reference from a cascaded LMX1204 design to drive the external clock of the AFE7950 RF sampling transceiver and compare performance of the design to the internal phase-locked loop (PLL) plus voltage-controlled oscillator (VCO) of that device.