Clock Chip (included , TCXO chip). Principal Electrical Scheme for AD9959 Shield Board v1.1. BOM List of Parts and Components for AD9959 Shield Board v1.1. We recommend to use RF Amplifier and Low Pass Filter with our DDS Shield Boards. RF Amplifier LNA 8-2000 MHz, GAIN = 20 dB, P = +20 dBm + LDO MMIC MRFA89 SOT-89.Low-Pass Filter LPF 7th Order Elliptical 1-1000Mhz 3.5 7 14 28 144 433MHz etc. AD9959 DDS Shield requires 4 Amplifiers and 4 Low Pass Filters for each channel!! Convenient and fast control with an encoder. Low harmonics no more than -60 dBc. An output RF transformer is used for the correct operation of the current mirror.
Signal lines TOP and Bottom, inner layers Ground and Power. Separate power supply for all analog and digital lines (1.8V and 3.3V), 5 pcs IC voltage stabilizers are used. Additionally, there is an RF Ferrite bead interchange.
High-speed decoupling Level converter and TTL 5V matching. Types of possible reference oscillators (choose one of them in the selector). XO Crystal 25 MHz 20 ppm internal oscillator with PLL up to 600 MHz. TCXO 40MHz (Supports 10 50 MHz) 1 ppm external oscillator PLL up to 600 MHz.
REF CLK IN external reference clock input, up to 600 MHz. (this source is NOT INCLUDED).
At the output of each channel is a transformer to reduce even harmonics. Additionally balancing transformer is used for XO, TCXO and REF CLK IN options. Easy to connect OLED display.Device control with one encoder and one button. The synthesizer is capable to generate sine wave. 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. This shield support overclocking the AD9959 core up to 600 MHz. DDS AD9959 Shield has ability to generate a signal up to 225 MHz with a core overclocking up to 600 MHz (to suppress harmonics, it is recommended to overclock the AD9959 for frequencies above 200 MHz). Since the intrinsic phase noise of DDS is obviously less than that of PLL generators, the final value is highly dependent on the clock source.
In order to achieve the values stated in the datasheet on AD9959, when designing our DDS AD9959 Arduino Shield, we strictly adhered to all recommendations from Analog Devices: PCB layout in 4 layers, separate power supply of all 4 power lines (3.3 V digital, 3.3 V analog, 1.8 V digital, and 1.8 V analog). Figure 18 shows the noise level when using the built-in PLL in DDS. The PLL multiplies the frequency of a 25 MHz generator by 20 times. We use a frequency 40 MHz (x12 Multiplier) or 50 MHz (x10 Multiplier) from TCXO which gives even more stability.
And figure 16 shows the noise level when using an external reference clock 500 MHZ, with the PLL off. That is, when using an external clock phase noise by 28 dBc better (lower).That is, when using an external clock phase noise by 30 dBc better (lower). Conclusion: when using external clocking, You can get much lower phase noise than using the built-in PLL. But do not forget that in order to achieve such results, increased requirements are put forward to the external generator. If you have ANY questions, PLEASE ASK US. 7 dBm to -60 dBm (on 50 Ohm load). 0.282 Vpeak-to-peak (at -7 dBm). USB or External Power Supply 5 7V DC 1A. 0 to 360 Degrees in 0.1 Degree Step. Reference clock sources (on choice).
XO-Crystal Oscillator, TCXO 1ppm Oscillator, or External Oscillator up to 600 MHz. DDS AD9959 Arduino Shield Spectrograms.GRA & AFCH DDS AD9959 Shield External Clock Source VS Internal Clock Source Comparison. GRA & AFCH DDS AD9959 Shield Oscillogram. DDS AD9959 All 4 Channels Outputs Shifted on 90 Degrees.
Arduino MEGA to Shield AD9959 Pinout Scheme. Block Scheme DDS AD9959 V1.1. DDS Arduino Shield AD9959 RF Signal Generator Overview. Please refer to full video Overview of our DDS AD9959 Shield RF Signal Generator on our YouTube channel:'GRA & AFCH.
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