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The AD9739 Evaluation Board connects to the Analog Devices Digital Pattern Generator (DPG2) to allow for quick evaluation of the AD9739. The DPG2 allows the user to create many types of digital vectors and transmit these at speed to the AD9739 in any of the AD9739 operating modes. The AD9739 evaluation board is configured over USB with accompanying PC software.
The DAC Software Suite plus AD9739 Update should be installed on the PC prior connecting the hardware to the PC. The DAC Software Suite is included on the Evaluation Board CD, or can be downloaded from the DPG web site at http://www.analog.com/dpg. This will install DPGDownloader (for loading vectors into the DPG2) and the AD9739 SPI Controller application.
To operate the board, a power supply capable of +5vdc, 2A should be connected to J17. A spectrum analyzer or an oscilloscope to view the DAC output should be connected to J1/J2 (See Figure 1). The diagram in Figure 1shows the location of each connection. A low jitter (< 0.5psec RMS) sine or square wave clock source should be connected to J3. The DC level of the clock is unimportant since the clock is AC-coupled on the evaluation board before the CLKP/N inputs. The included USB cable should be used to connect the Evaluation Board to a PC.
The AD9739 Evaluation Board has four versions: “Normal” (AD9739-EBZ), “Mix Mode” (AD9739-MIX-EBZ), and “CMTS” (AD9739-CMTS-EBZ) and the newer AD9739-R2-EBZ.
This configuration was for applications targeting cable infrastructure applications up to 1GSPS. In this configuration, a JTX-2-10T transformer is used, which is effectively a balun and center-tap transformer in one package. A filter network is used to help balance the impedance between the DAC and transformer, and helps to knock down some of the images in the 2nd Nyquist zone. These images would otherwise end up folding back into the desired 1GHz bandwidth (depending on the location of the desired carriers). The output configuration for this application is shown below.
This quick-start will setup a single-tone output from the AD9739 to provide a brief introduction to the part, as well as a basic functionality test. Note that while this is a valid setup on all three versions of the board, it should not be used for performance measurements. For performance testing, ensure that an appropriate vector and frequency plan is used with the correct board version. To begin, open the AD9739 SPI application (Start > Programs > Analog Devices > AD9739-EBZ > AD9739 SPI). Connect a +5Vdc power supply to J17, and connect a 2GHz, 0dBm clock to J3.
In order to optimize and lock the Mu Controller, it is only necessary to have the DAC clock running (no data needs to be presented). Click the MU_ENA button in the MU Controller section of the SPI controller, as shown in Figure 5. Then run the SPI controller by clicking on the Run button () in the upper left of the screen.
Open DPGDownloader (Start > Programs > Analog Devices > DPG > DPGDownloader). Ensure that “AD9739” is selected in the Evaluation Board drop-down list. For this evaluation board, “LVDS” is the only valid Port Configuration, and will be selected automatically. The Data Clock Frequency display should read approximately 500MHz. Click on Add Generated Waveform, and then Single Tone, as shown below. A Single Tone panel will be added to the vector list. Start by entering the Clock Frequency (2GHz in this case). You can enter 2G in the box. Next, enter 200MHz (200M) as the desired frequency of the tone. The DAC Resolution should be set at 14 bits. Next, in the lower portion of the screen, select “1: Single Tone” as the Data Vector. The other options can be left at their default. After the DPG2 is correctly setup, click the Download button () in the lower right, then the Play button () to begin vector playback into the AD9739.
Once the pattern is loaded into the DPG2 and running, the final step is to enable the LVDS Controller. In the AD9739 SPI controller, enable the RCV_LOOP and RCV_ENA buttons. Click the Run button (). Once the run is complete, the RCVR LCK and RCVR TRX ON indicators should be green, as shown below.
Another way to verify that the controller is in the correct spot (and not on the edge) is to check the status of the four status bits which sample the rising edge of the DCI at four different phases. DCI PHS1 should always be high, and DCI PHS3 should always be low. The other bits will toggle as the LVDS controller searches for the correct timing. The ideal case is shown to the right Increasing the value of the FINE_DEL_SKEW allows for a wider search around the DCI edge, and should reduce the toggling on PHS0 and PHS2. This is usually required when the DCI signal has a lot of jitter.
The SPI controller software is broken up into numerous sections. Several of them are described here, as they pertain to the evaluation board. For complete descriptions of each SPI register, see the AD9739 datasheet. In the interest of continuous quality improvements, the images below may not exactly match your version of the software.
These bits (shown to the right) control the operation of the SPI port on the AD9739, as well as the master reset and individual power-down bits. Changing the SDIO DIR or DATADIR bits will cause the SPI controller application to stop functioning correctly. Do not change these bits. The Reset button is “sticky”, that is, the part will stay in reset for as long as the button is enabled. To reset the part, set this bit, run the SPI controller, then unset this bit and run the controller again.
The Controller Clock controls enable the Mu Controller and LVDS controllers. For normal operation, both of these should be enabled. The Clock GEN PD switch powers down the clocking structure, and should be left disabled for normal use. The DAC current ouput has an adjustable full-scale value. The FSC Setoption allows for this adjustment. After running the SPI controller, the full-scale current in miliamps will be displayed here.
optimal setting is negative 6 (max of 16) . Register 0x27 bits 0-4
search. It is best to set it to the middle of the delay line . The maximum Mu delay is 432, so set these bits to approximately 220.
Sets the Mode in which the Controller searches:
|Mode||Register: 0x26 Bits 4, 5|
|Search and Track (Optimal Setting)||0x00|
Sets the Mode in which the search for the optimal phase is performed:
|Search Mode||Register: 0x27 – Bits 5, 6|
|Up/Down (Optimal Setting)||0x10|
Search GB: sets a GB from the beginning and end of the Mu Delay line in which the Mu controller will not enter into unless it does not find a valid phase outside the GB. Register 0x29 bits 0-4. Optimal value is Decimal 11.
Tolerance: Sets the Tolerance of the phase search. Register 0x29 bit 7
ContRST: Controls whether the controller will reset or continue if it does not find the desired phase
Phase Detector Enable: Register 0x24 bit 5. Enables the Phase Detector (Set to 1 to enable the Phase Detector)
Phase Detector Comparator Boost: Optimizes the bias to the Phase Detector (Set to 1 to enable)
Bias: Register 0x24 Bits 0-3: Manual Control of the bias if the Boost control is not enabled
Duty Cycle Fix: Register 0x25 Bit 7 Enables the duty cycle correction in the Mu Controller. Recommended to always enable (Set to 1 to enable)
Direction: Register 0x25 Bit 6 Sets the direction that the duty cycle will be corrected
Offset: Register Register 0x25 Bit 0-5 Sets the Duty Cycle Correction manually if Fix is not enabled
The status read back bits for the mu controller are as follows:
In order to read back the present MU Delay and phase value, it is necessary to set the Read bit high and then low before the values can be read back:
In order to use the Mu controller in manual mode the following bits are utilized:
Register 0x12 Optimal value is 166 which is the center of the delay line. The maximum delay value is d333 or x14D.
To ensure that the LVDS Controller is locked and tracking check the status of the following bits: