This user guide describes the evaluation boards, AD9627-125EBZ, AD9627-150EBZ, and AD6655-125EBZ that are used to evaluate the following Analog Devices, Inc., products: AD9627, AD6655, and AD6653. These evaluation boards provide all of the support circuitry required to operate these parts in their various modes and configurations. The application software used to interface with the devices is also described.
The AD9627, AD6655, and AD6653 data sheets provide additional information and should be consulted when using the evaluation board. All documents and software tools are available at www.analog.com/hsadcevalboard. For additional information or questions, send an email to firstname.lastname@example.org.
Before using the software for testing, configure the evaluation board as follows:
This evaluation board comes with a wall-mountable switching power supply that provides a 6 V, 2 A maximum output. Connect the supply to the rated 100 V ac to 240 V ac wall outlet at 47 Hz to 63 Hz. The output of the supply is a 2.1 mm inner diameter circular jack that connects to the PCB at J16. Once on the PC board, the 6 V supply is fused and conditioned before connection to six low dropout linear regulators that supply the proper bias to each of the various sections on the board.
External supplies can be used to operate the evaluation board by removing L1, L3, L4, and L13 to disconnect the voltage regulators supplied from the switching power supply. This enables the user to individually bias each section of the board. Use P3 and P4 to connect a different supply for each section. At least one 1.8 V supply is needed with a 1 A current capability for AVDD and DVDD; a separate 1.8 V to 3.3 V supply is recommended for DRVDD. To operate the evaluation board using the AD8352 option, a separate 5.0 V supply (AMP VDD) with a 1 A current capability is needed. To operate the evaluation board using the alternate SPI options, a separate 3.3 V analog supply (VS) is needed, in addition to the other supplies. The 3.3 V supply (VS) should have a 1 A current capability, as well. Solder Jumper SJ35 allows the user to separate AVDD and DVDD, if desired.
When connecting the clock and analog source, use clean signal generators with low phase noise, such as the Rohde & Schwarz SMA100A signal generators or the equivalent. Use 1 m long, shielded, RG-58, 50 Ω coaxial cable for making connections to the evaluation board. Enter the desired frequency and amplitude for the ADC. The AD9627 evaluation board from Analog Devices, Inc., can accept a ~2.8 V p-p or 13 dBm sine wave input for the clock. When connecting the analog input source, it is recommended that a multipole, narrow-band, band-pass filter with 50 Ω terminations be used. Band-pass filters of this type are available from TTE, Allen Avionics, and K & L Microwave, Inc. Connect the filter directly to the evaluation board, if possible.
The parallel CMOS outputs interface directly with the Analog Devices standard ADC data capture board (HSC-ADC-EVALCZ). For more information on the ADC data capture boards and their optional settings, visit www.analog.com/FIFO.
Connect the switching power supply that is provided in the evaluation kit between a rated 100 V ac to 240 V ac wall outlet at 47 Hz to 63 Hz and P500.
The evaluation board is set up for a double balun configuration analog input with optimum 50 Ω impedance matching from 70 MHz to 200 MHz. For more bandwidth response, the differential capacitor across the analog inputs can be changed or removed (see Table 13). The common mode of the analog inputs is developed from the center tap of the transformer via the CML pin of the ADC (see the Analog Input Considerations section).
VREF is set to 1.0 V by tying the SENSE pin to ground by adding a jumper on Header J5 (Pin 1 to Pin 2). This causes the ADC to operate in 2.0 V p-p full-scale range. To place the ADC in 1.0 V p-p mode (VREF = 0.5 V), a jumper should be placed on Header J4. A separate external reference option is also included on the evaluation board. To use an external reference, connect J6 (Pin 1 to Pin 2) and provide an external reference at TP5. Proper use of the VREF options is detailed in the Voltage Reference section.
RBIAS requires a 10 kΩ resistor (R503) to ground and is used to set the ADC core bias current.
The default clock input circuitry is derived from a simple balun-coupled circuit using a high bandwidth 1:1 impedance ratio balun (T5) that adds a very low amount of jitter to the clock path. The clock input is 50 Ω terminated and ac-coupled to handle single-ended sine wave inputs. The transformer converts the single-ended input to a differential signal that is clipped before entering the ADC clock inputs. When the AD9627 input clock divider is utilized, clock frequencies up to 625 MHz can be input into the evaluation board through Connector S5.
To enable the power-down feature, connect J7, shorting the PDWN pin to AVDD.
The CSB pin is internally pulled up, setting the chip into external pin mode, to ignore the SDIO and SCLK information. To connect the control of the CSB pin to the SPI circuitry on the evaluation board, connect J21, Pin 1 to J21, Pin 2.
If the SPI port is in external pin mode, the SCLK/DFS pin sets the data format of the outputs. If the pin is left floating, the pin is internally pulled down, setting the default data format condition to offset binary. Connecting J2, Pin 1 to J2, Pin 2 sets the format to twos complement. If the SPI port is in serial pin mode, connecting J2, Pin 2 to J2, Pin 3 connects the SCLK pin to the on-board SPI circuitry
If the SPI port is in external pin mode, the SDIO/DCS pin sets the duty cycle stabilizer. If the pin is left floating, the pin is internally pulled up, setting the default condition to DCS enabled. To disable the DCS, connect J1, Pin 1 to J1, Pin 2. If the SPI port is in serial pin mode, connecting J1, Pin 2 to J1, Pin 3 connects the SDIO pin to the on-board SPI circuitry.
Two alternate clocking options are provided on the AD9627 evaluation board. The first option is to use an on-board crystal oscillator (Y1) to provide the clock input to the part. To enable this crystal, Resistor R8 (0 Ω) and Resistor R85 (10 kΩ) should be installed, and Resistor R82 and Resistor R30 should be removed. A second clock option is to use a differential LVPECL clock to drive the ADC input using the AD9516 (U2). When using this drive option, the AD9516 charge pump filter components need to be populated (see Figure 79). Consult the AD9516 data sheet for more information. To configure the clock input from S5 to drive the AD9516 reference input instead of directly driving the ADC, the following components need to be added, removed, and/or changed.
This section provides a brief description of the alternative analog input drive configuration using the AD8352. When using this particular drive option, some additional components need to be populated. For more details on the AD8352 differential driver, including how it works and its optional pin settings, consult the AD8352 data sheet.
To configure the analog input to drive the AD8352 instead of the default transformer option, the following components need to be added, removed, and/or changed for Channel A. For Channel B the corresponding components should be changed.
After configuring the board, set up the ADC data capture using the following steps:
Figure 2. VisualAnalog, New Canvas Window
Figure 4. VisualAnalog Window Toolbar, Collapsed Display
Figure 5. VisualAnalog, Main Window Expanded Display
After the ADC data capture board setup is complete, set up the SPI controller software using the following procedure:
Figure 6. SPI Controller, CHIP ID(1) Box
Figure 8. SPI Controller, ADCBase0 Page
Figure 9. SPI Controller, Example ADC A Page
The next step is to adjust the amplitude of the input signal for each channel as follows:
If the FFT plot appears abnormal, do the following:
If the FFT appears normal but the performance is poor, check the following:
If the FFT window remains blank after Run is clicked, do the following:
If VisualAnalog indicates that the FIFO Capture timed out, do the following: