JAJSF03K September 2011 – December 2023 LMK03806
PRODUCTION DATA
In the LOOPFILTER box, there are options for displaying a bode plot, simulating phase noise, and re-calculating loop filter values. Selecting the ‘Design a Loop Filter’ button brings up a window where a target bandwidth and phase margin can be entered and the tool will re-design the loop filter component values to converge to the specified targets. Component values can also be manually entered and the tool will calculate the resulting loop filter parameters.
For this example, a custom phase noise plot was uploaded based on measured data for the reference oscillator input. Fpd was set to 20 MHz and loop filter was optimized to achieve a loop bandwidth of 62 kHz and phase margin of 76°. The loop filter values used were C1 = 220 pF, C2 = 18 nF, R2 = 820 Ω, C3 = 10 pF, R3 = 200 Ω, C4 = 10 pF, and R4 = 200 Ω. The charge pump current was set to 3.2 mA.