ADF4351 35MHz-4.4GHz RF Signal Generator Board with OLED Display

Specifications

• Chipset:  ADF4351 
• Frequency Range: 35 MHz to 4400 MHz (4.4 GHz)
• Module step: 100KHz (minimum)
• Frequency error: ±1KHz
• Display: Onboard high-contrast OLED screen
• Control Interface: 5 tactile push-buttons for standalone configuration
• Output Interface: 2x SMA Female connectors (Differential output, often configured as primary and auxiliary)
• Power Supply: 5V via Mini-USB or dedicated PCB pin headers
• Reference Clock: Onboard 25MHz active crystal oscillator
• Output Power: Programmable (typically -4dBm to +5dBm depending on frequency and configuration)
• Form Factor: Compact PCB with corner mounting holes

Applications

• Ham Radio & SDR: Provide a stable local oscillator (LO) or test signal for Software Defined Radios.
• VNA Calibration: Generate precise marker frequencies for Vector Network Analyzers.
• Clock Generation: Drive high-speed ADCs or DACs requiring ultra-low jitter clocks.
• RF Shielding Tests: Act as a continuous wave (CW) beacon to test enclosure shielding effectiveness.

Unlock New Capabilities

• Past Projects: If you've previously used NE555 timers or standard Si5351 modules to generate signals up to 160MHz, you know the limitations of lower-frequency hardware.
• Feature Upgrade: Upgrading to the ADF4351 completely unlocks the microwave spectrum for your lab. You can now test Wi-Fi band antennas, 2.4GHz filters, and satellite downlinks with a single board.
• Effort/Requirements: Intermediate. Operating it via the buttons is beginner-friendly, but analyzing the high-frequency RF output requires an oscilloscope or spectrum analyzer capable of measuring up to 4.4GHz.

Virtual Technician & Wiring Guide

• Safety Warning: Never connect the RF output directly to a sensitive receiver without ensuring the power levels (dBm) are within safe limits. Use inline attenuators if necessary.
• Powering Up: Simply plug a 5V source into the Mini-USB port. The OLED will immediately boot up.

Standalone Navigation: * Left / Right Buttons: Move the cursor across the digits on the OLED.

• Up / Down Buttons: Increase or decrease the selected digit's value to set the frequency.
• OK Button: Confirm the selection and output the signal.

• External Control: The board exposes SPI pins (CLK, DATA, LE, CE) allowing you to bypass the buttons and control the ADF4351 directly via an Arduino or ESP32 if automated sweeping is required.

Package Includes:

• 1 x  ADF4351 35MHz-4.4GHz RF Signal Generator Board with OLED Display 

Frequently Asked Questions (FAQ)

• What is the exact frequency range of this ADF4351 board?
  The module can generate signals from 35 MHz all the way up to 4400 MHz (4.4 GHz).
• How do I power the ADF4351 OLED module?
  You can power it using a standard 5V Mini-USB cable or by supplying 5V to the dedicated pins on the board.
• Can I control this board without a microcontroller?
  Yes, the primary feature of this specific board is its standalone capability. The STM32 onboard handles the OLED and buttons, allowing you to set frequencies manually.
• What do the 5 push buttons do?
  They act as a directional pad. Left/Right moves the cursor, Up/Down changes the frequency value, and the center/OK button confirms the output.
• What is the output impedance of the SMA connectors?
  The RF outputs are matched for standard 50-ohm impedance.
• Does this board output a sine wave or a square wave?
  At higher frequencies, it approaches a sine wave, but at lower frequencies (due to the fundamental VCO dividers), the output is closer to a square wave.
• Can I program this module using an Arduino?
  Yes. You can bypass the onboard microcontroller and send SPI commands directly to the ADF4351 chip using the exposed pin headers.
• What is the tuning resolution/step size?
  Using the onboard buttons, the typical resolution is 10kHz to 100kHz depending on the firmware version loaded on the board's controller.
• Is the output power adjustable?
  Through SPI programming, the chip supports 4 power levels (-4dBm to +5dBm). However, via the standalone OLED interface, it usually outputs at a fixed default power level.
• Can I use this for FM or AM modulation?
  No, the ADF4351 is designed to be a continuous wave (CW) RF source. It does not have built-in analog modulation capabilities.
• Does the board save the last set frequency after power off?
  Yes, most versions of this board's firmware save the last inputted frequency in EEPROM and restore it upon boot.
• What is the reference clock frequency on this board?
  The board includes a standard 25 MHz active crystal oscillator as the baseline reference for the PLL.
• Can I use an external reference clock?
  Yes, but it requires desoldering the onboard 25MHz crystal and injecting your external clock (like a 10MHz GPSDO) into the reference input trace.
• How many output channels does it have?
  It has two SMA outputs. The ADF4351 provides a differential output (RFoutA+ and RFoutA-), which are routed to the two SMAs.
• What is the maximum output power?
  The maximum programmable output power is approximately +5 dBm, though this varies slightly across the massive frequency spectrum.
• Can it perform frequency sweeping standalone?
  The basic standalone firmware is generally for fixed-frequency generation. For automated sweeping, you will need to control it via SPI with an external microcontroller.
• Are both SMA outputs identical?
  They are complimentary differential outputs. For most basic single-ended test applications, you can use either one.
• What is the operating voltage of the internal logic?
  While the board takes 5V input, the internal regulators drop this to 3.3V for the ADF4351 chip and microcontroller logic.
• Why is the OLED screen not turning on?
  Ensure your USB cable is providing a solid 5V. Some computer USB ports may not provide enough initial current; try a dedicated USB wall adapter.