PLL Frequency Calculator

Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Calculate PLL frequency plan values including PFD frequency, VCO frequency, output frequency, total multiplication/division ratio, and VCO range status.

Input Parameters

Reference Clock

MHz

Input reference clock frequency.

Input Divider M

Reference divider before phase detector.

Feedback Multiplier N

PLL feedback multiplication factor.

Output Divider P

Output divider after VCO.

VCO Minimum

MHz

Minimum allowed VCO frequency from datasheet.

VCO Maximum

MHz

Maximum allowed VCO frequency from datasheet.

Results

PFD Frequency

VCO Frequency

PLL Output Frequency

Total Ratio

VCO Range Status

Design Note

Equations Used

PFD Frequency: Fpfd = Fref / M

VCO Frequency: Fvco = Fpfd × N

Output Frequency: Fout = Fvco / P

Total Ratio: Fout / Fref = N / (M × P)

Frequently Asked Questions (FAQ)

Q1: What does a PLL frequency calculator do?
It calculates phase detector frequency, VCO frequency, and output frequency from PLL divider values.

Q2: Why must VCO frequency be checked?
PLL devices only lock correctly within a specified VCO operating range.

Q3: What is the PFD frequency?
The phase-frequency detector frequency is the divided reference clock used by the PLL control loop.

Q4: Does this calculate phase noise or jitter?
No. It calculates frequency planning only. Jitter and phase noise require PLL datasheet models or simulation.

Q5: Can this be used for MCU PLL setup?
Yes, as long as you use the divider definitions and limits from the specific MCU or clock generator datasheet.

Disclaimer: This calculator checks basic PLL frequency planning only. Real PLL design must verify device-specific divider rules, VCO range, PFD limits, lock range, loop filter, phase noise, jitter, and clock tree constraints.

Previous Tool SPI Clock Calculator Next Tool Clock Divider Calculator

PRODUCT

PHONE

USER