Dds Ad9912 Arduino Shield Rf Signal Generator

DDS (Direct Digital Synthesis) Analog Devices AD9912 Arduino Shield by GRA & AFCH
This device is designed to ensure seamless integration with Arduino MEGA 2560
It does not require any extra wires or converters to work properly
For maximum performance we recommend Ultra-low noise reference oscillator RCLN1000D-222
All AD9912 pins are connected to the Arduino MEGA pins
With this you can fully reveal all the capabilities of the DDS9912 Shield
PCB Design Schematics Case and Software made by GRA & AFCH

Open-source Software available on our GitHub repository: [link removed by eBay]
DDS9912 Firmware compilation and uploading to Arduino Mega Tutorial: youtu.be/Zn1xLlvlVXE
Video review of DDS9912 Shield on our YouTube channel: youtu.be/_MUsmr0cAD4

• RF Unit DDS9912 [DDS9912 Shield Board]
• Display [OLED] (0,94″ or 1,54″) (optional, choose in selector)
• Clock Source (XO, TCXO, EGEN, OCXO) (optional, choose in selector)
• Arduino Control Board [MEGA 2560] (optional, choose in selector)
• Power Supply [DC 7.5V/2A] [US, EU, UK] [AC plug] (optional, choose in selector)
• Operating Instruction

1. XO – Crystal 25 MHz 20 ppm internal oscillator with PLL at 1 GHz
2. TCXO – 50 MHz 1 ppm oscillator PLL x 20 at 1 GHz
3. REF CLK IN – external generator up to 1 GHz
   (to connect an external clock source of up to 1.3 GHz, the source itself is NOT INCLUDED)
   
   

• Oscillator Ultra Low Phase Noise Fout=100MHz -154dBc/Hz @ 10khz, Fout=400MHz -145dBc/Hz @ 10khz (external reference clock – RCLN1000D-222)
• Local oscillator (LO) for HAM Radio
• Receiver/Transmitter communications
• Agile local oscillator (LO) frequency synthesis
• For teaching students at Universities and Institutes
• Secure communications
• Test and measurement equipment

• Support of OLED display (selectable in options)
• One encoder for controlling all functions through a graphical menu
• The synthesizer is capable to generate Sine Wave, CMOS and HSTL signals
• Differential HSTL Output up to 1 GHz
• CMOS Output to up to 200 MHz
• The software allows you to select and configure the frequency of the clock generator through the user menu
  (without the need to recompile the program)
• Any settings can be stored in non-volatile EEPROM memory (located at Arduino Mega)
• Basic settings are applied and saved automatically
• Expanded and convenient DDS Clock source menu
• This Shield Board support overclocking of the AD9912 core up to 1.3 GHz (heatsink is recommended)
• The DDS9912 Shield has the capability to generate a signal with a frequency of up to 600 MHz,
  with a core overclocking potential of up to 1.3 GHz (when the output frequency exceeds 400 MHz,
  it is recommended to overclock the DDS core for harmonic suppression)
• Standard Mode: up to 400 MHz sine wave output, 1 GSPS (1.0 GHz) internal or external clock speed
• Overclocking Mode: up to 600 MHz sine wave output, up to 1.3 GSPS (1.3 GHz) internal or external clock speed
• Output Filter LPF 9-order
• Spur Killer* 2 channels to suppress spurs in the frequency spectrum* (not yet implemented)
• Integrated 14 bit DAC 48 bit frequency tuning word with 4 μHz resolution 0.000004Hz (optional)

• Ensured low harmonic level with levels not exceeding -70dBc,
  this is due to the use of an output RF transformer for optimal current mirror operation
• Low-Noise LDO Stabilizers with separate power supply for all analog and digital lines (1.8V and 3.3V),
  they utilizes 8 IC voltage stabilizers; additionally there is an RF Ferrite bead interchange
• Additional balancing transformer used for TCXO and REF CLK IN options
• 4 layered PCB with signal lines on Top and Bottom and inner layers Ground and Power
• High-speed decoupling Level converter and TTL 5V matching
• The built-in 50-ohm resistors in the AD9912 chip provide better noise and harmonic performance compared to the AD9910
• Remote control of the DDS Generator through a USB connection and PC using the terminal serial port

* when overclocking the core to 1.3 GHz

This parameter is very important and interesting for those who buy and want to use DDS9912 Shield Board.
Since the internal phase noise of DDS is obviously less than that of PLL generators, the final value are highly dependent on the clock source.
In order to achieve the values stated in the datasheet on AD9912, when designing our DDS9912 Arduino Shield, we strictly adhered to all recommendations from Analog Devices:

PCB layout in 4 layers, 8 low-noise voltage regulators for all power lines (3.3V digital, 3.3V analog, 1.8V digital, and 1.8V analog and etc.).
All phase-noise measurements were performed using a PN2060, and we found that our results are very close to the values specified in the AD9912 datasheet.

Let’s compare on this diagram the phase noise plots at the output of the DDS9912 when clocked by the internal PLL and when clocked by the reference ultra-low-noise oscillator RCLN1000D-222.
At a 10 kHz offset from the 100 MHz carrier: with the internal PLL system engaged, the phase noise level is -133 dBc/Hz, while with the PLL system disengaged and using external clocking from RCLN1000D-222, the phase noise is -155 dBc/Hz. This means that using an external clock signal from RCLN1000D-222 results in a phase noise that is 22 dBc/Hz better (lower).

For the same output frequency, but at a 1 MHz offset from the carrier, with the internal PLL system engaged, the phase noise level is -131 dBc/Hz, while with the PLL system disengaged and using external clocking, the phase noise is -168 dBc/Hz.
This means that using external clocking results in phase noise that is 37 dBc/Hz better (lower)

Now let’s compare the same phase noise plots, but at a higher output frequency — 400 MHz.

At a 10 kHz offset from the carrier: with the internal PLL system engaged, the phase noise level is -121 dBc/Hz, while with the PLL system disengaged and using external clocking from RCLN1000D-222, the phase noise is -145 dBc/Hz. This means that using an external clock signal from RCLN1000D-222 results in a phase noise that is 24 dBc/Hz better (lower).

For the same output frequency, but at a 1 MHz offset from the carrier, with the internal PLL system engaged, the phase noise level is -119 dBc/Hz, while with the PLL system disengaged and using external clocking, the phase noise is -158 dBc/Hz.
This means that using external clocking results in phase noise that is 39 dBc/Hz better (lower).

Conclusion:
When using an external clock, you can achieve much lower phase noise than with the built-in PLL, and this difference becomes even more pronounced as the output frequency increases.
But do not forget that in order to achieve such results, increased requirements are put forward to the external oscillator.
For maximum performance we recommend our Ultra-low-noise reference oscillator 1GHz RCLN1000D-222.

The simplest method to increase the power is connecting an external RF signal Amplifier, such as the MMIC MRFA89.
It allows obtaining a DDS signal output power of up to +20 dBm.

IMPORTANT: Since the MMIC MRFA89 Amplifier has maximum output power of +20 dBm and gain of 20 dB, the recommended maximum input signal level is 0 dBm.

NOTE: as most amplifiers generate harmonics, it is advised to connect an LPF Filter to the Amplifier output for harmonic suppression.
For example, one from the LPF 7th Order Elliptical series that we offer.

Low-Pass Filter LPF 7th Order
Elliptical 1-1000Mhz 3.5, 7, 14, 28, 144, 433MHz etc
for RF Amlifier, Receiver, Transmitter, Mixer, Transceiver, Antenna:

ebay.com/itm/164902154239

RF Amplifier 8-2000 MHz
GAIN = 20 dB, P = +20 dBm
MIC MRFA89 SOT-89 [GOLD PLATED]:

ebay.com/itm/165965022658

Starting with version 1.02, the ability to control via the serial port has been added.

F – Set Frequency in Hz (100000 – 500000000)
H – Set HSTL Output: 0 – OFF, 1 – ON, 2 – Doubler ON
C – Set CMOS Output: 0 – OFF, 1 – ON
D – Set CMOS Divider (1 – 65353)
P – Set Output Power in dBm (-7 – +4)
M – Get Model
E – Enable Outputs (ALL)
S – Shut down Outputs (ALL)
V – Get Firmware Version
h – Help
; – Commands Separator

Example:
F100000;P-2
Set Frequency to 100 kHz, and Output Power to -2 dBm.
Any number of commands in any order is allowed.

Speed – 115200 Bouds
Data Bits – 8
Stop Bits – 1
Parity – No
DTR – OFF

An example of setting up a serial port in the Windows console:

mode COM3 baud=115200 DTR=OFF Data=8

Usage example:
echo F100000000 > COM3

An example of setting up a serial port in the Ubuntu:

sudo usermod -aG dialout $USER_NAME$
sudo chmod a+rw /dev/ttyUSB0
sudo stty -F /dev/ttyUSB0 115200 cs8 ixoff -hupcl -echo

Usage example:
echo “F100000000” > /dev/ttyUSB0

example of command prompt with serial commands for AD9912 DDS RF Unit

 Full Overview of AD9912 Shield Board available on our YouTube channel: "GRA & AFCH"