ZHCSEK4E December 2015 – August 2022 LMX2582
PRODUCTION DATA
The lowest PLL flat noise is achieved with a low-noise 200-MHz input signal. If only a low-noise input signal with lower frequency is available (for example a 100-MHz source), you can use the low noise OSCin doubler to attain 200-MHz phase detector frequency. Because PLL_flat = PLL_FOM + 20 × log(Fvco/Fpd) + 10 × log(Fpd / 1Hz), doubling Fpd theoretically gets –6 dB from the 20 × log(Fvco/Fpd) component, +3 dB from the 10 × log(Fpd / 1Hz) component, and cumulatively a –3-dB improvement.