For code examples also see here


http://pa0rwe.nl/?page_id=65


and here


 http://f6kbf.free.fr/html/ADF4251%20and%20Arduino_Fr_Gb.htm


ORDERS For a complete DIY KIT  USD 29.00


The KIT includes a  high-quality ENIG FR4 PCB (25 x 38 mm) that comes with all SMD components factory pre-soldered. RF capacitors are used for all the circuits.  

Three SMA female connectors (long shaft) with nuts and washers are also supplied, unsoldered. 

The shipping is with registered mail  (your signature is required upon delivery). 

I usually ship the next day and it takes about a week to 10 days for USA or Australia, less than a week for Europe.​

SV1AFN Design Lab

ADF4351 PLL

Synthesizer Module


35MHZ to 4400 MHZ

with ext. REF input - Simple SPI interface


Make a VFO, Clock Gen etc. fast



Based on the Analog Devices ADF4351 chip, this small module is a complete PLL Synthesizer working from 35 MHZ to 4..4 GHZ.

The ADF4351 allows implementation of fractional-N or integer-N phase-locked loop (PLL) frequency synthesizers when used with an external loop filter and external reference frequency. The ADF4351 has an integrated voltage controlled oscillator (VCO) with a fundamental output frequency ranging from 2200 MHz to 4400 MHz. In addition, divide-by-1/-2/-4/-8/-16/-32/-64 circuits allow the user to generate RF output frequencies as low as 35 MHz. Control of all on-chip registers is through a simple 3-wire interface. The ADF4351 module draws under 60 mA - 100 at 3.3 VDC, depending on the output power set and if the frequency dividers are being used.


The PCB dimensions are only 25 x 38 mm and it requires an external frequency reference that can be applied to J5 SMA female connector.


A small Arduino or any other MCU can be used to control the ADF4351 module, and the "cheat sheet" provided at the end of this page is really a great help. Considering its small size and the simplicity this module provides, a user can quickly produce an RF signal, phase-locked to his reference and also to control the output power, this module can find many applications like a VFO, fixed frequency oscillator, ADC or DAC clock etc.

Interesting features are the capability to adjust phase, to set low spur or low noise and of course the capability to select Integer-N for lowest phase noise.

















ADF4351 Programming:

I have found this "cheat sheet" that helps, see it here: