National Semiconductor ADC081500DEV Instruction Manual
March 24, 2006
Revision A
Development Board Instruction Manual
ADC081500DEV - Single 8-Bit, 1.5 GSPS, 1.2W A/D Converter with
Xilinx Virtex 4 (XC4VLX15) FPGA
© Copyright 2006 National Semiconductor Corporation
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ADC081500EVAL BOARD USER MANUAL – TABLE OF CONTENTS
ADC081500EVAL BOARD USER MANUAL – TABLE OF CONTENTS........................2
1.0 Introduction........................................................................................................................... 3
2.0 Board Assembly.................................................................................................................... 3
3.0 Quick Start............................................................................................................................ 4
4.0 Functional Description .......................................................................................................... 4
4.1 Input circuitry...................................................................................................................... 4
4.2 ADC reference.................................................................................................................... 4
4.3 ADC clock........................................................................................................................... 4
4.4 Digital Data Output............................................................................................................. 4
4.5 Power Requirements..........................................................................................................5
4.6 Power Supply Connections................................................................................................ 5
5.0 Obtaining Best Results ......................................................................................................... 5
5.1 Clock Jitter.......................................................................................................................... 5
6.0 Evaluation Board Specifications ........................................................................................... 5
7.0 Schematic Drawing ADC081500DEV – Onboard Clock (VCO + PLL) ................................. 6
7.1 Schematic Drawing ADC081500DEV – Analog Inputs (I,Q) & Digital Trigger Input........... 7
7.2 Schematic Drawing ADC081500DEV – ADC connected to Virtex4 FPGA ........................ 8
7.3 Schematic Drawing ADC081500DEV – USB Interface...................................................... 9
7.4 Schematic Drawing ADC081500DEV – Power Supplies 1 .............................................. 10
7.5 Schematic Drawing ADC081500DEV – Power Supplies 2 .............................................. 11
7.6 Schematic Drawing ADC081500DEV – Expansion Header Interface.............................. 12
8.0 Bill of Materials (Page 1 of 2)..............................................................................................13
8.1 Bill of Material (Page 2 of 2)............................................................................................. 14
9.0 Using the Wavevision4 software with the ADC081500DEV ............................................... 15
9.1 Getting Started................................................................................................................. 15
9.2 Control Panel.................................................................................................................... 17
9.3 Serial Control Mode.......................................................................................................... 19
9.4 Capturing Waveforms....................................................................................................... 20
10.0 Appendix A - Hardware Information.................................................................................. 20
10.1 LED functions................................................................................................................. 20
10.2 Expansion Header.......................................................................................................... 21
10.3 System Block Diagram................................................................................................... 22
11.0 Appendix B - Installing and running the Wavevision 4 software....................................... 23
11.1 Install the WaveVision Software..................................................................................... 23
11.2 Java™ Technology......................................................................................................... 23
11.3 Automatic Device Detection & Configuration ................................................................. 23
11.4 Windows Driver.............................................................................................................. 23
12.0 Appendix C - Using WaveVision Plots.............................................................................. 24
The Waveform Plot................................................................................................................. 24
The FFT Plot .......................................................................................................................... 24
FFT Options ........................................................................................................................... 25
Histogram Plots...................................................................................................................... 26
Information Viewer ................................................................................................................. 26
Data Import and Export..........................................................................................................26
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1.0 Introduction
The ADC081500DEV Board is designed to
allow quick evaluation and design development
of National Semiconductor’s ADC081500 8-bit
Analog-to-Digital Converter. This device is
specified for 1.5 GSPS operation.
This development board is designed to function
with National Semiconductor’s WaveVision
Software, for fast evaluation. It requires only 3
connections to get started: a Power Supply, a
USB Interface to PC and a Signal Source. A
1.5GHz Clock generator is provided on board
and the system also allows an external clock to
be used if alternative sample rates are required.
Analog I Channel
Input
Clock Input
The ADC connects to a Xilinx Virtex4 FPGA
which stores up to 4K of data from each
channel before transferring it through the USB
interface to the PC.
2.0 Board Assembly
The ADC081500 Development Board comes in
a low profile plastic enclosure and requires no
assisted cooling due to its low power
consumption. The ADC081500 device is
configured entirely through software and also
allows changes to easily be made to the FPGA
configuration to enable system development.
USB
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Trigger Input
PWR
SWITCH
PWR
INPUT
Figure 1 Component Placement & Front Panel
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3.0 Quick Start
Refer to Figure 1 for locations of the power
connection, signal input and USB port.
IMPORTANT NOTE:
Install the Wavevision 4 Software before
connecting this product to the PC. See
Appendix B – Installing Wavevision.
For quick start operation:
1. Connect the 12V DC power source
(included with the development board) to the
rear Power Connector labeled (8-12V DC).
2. Connect a stable sine wave source capable
of supplying the desired input frequencies at
up to 8 dBm. Connect this signal to the front
panel SMA connector labeled “I CH.”
through a band pass filter. The exact level
needed from the generator will
depend upon
the insertion loss of the filter used.
3 Connect the USB cable (included) from the
USB port to the PC. If this is the first time
the board has been connected, Windows
may install the drivers for this product at this
time.
5. Push the Power Switch to the ON position
on the rear panel and check that the Green
LED between the switch and the power
connector illuminates.
6. Start the Wavevision 4 Software
7. Once loaded the “Firmware Download”
Progress bar should be displayed. See
Appendix B for more information.
8. Upon Firmware Download completion, the
control panel for the board should
automatically be displayed on the PC and
the CLK LED on the front panel should be
flashing.
8. Set the signal source for the analog input to
8 dBm at the desired frequency. Observe
the ‘Out of Range’ LED “OVR” on the front
panel is illuminated. If this LED is not on,
increase the input signal source until it is.
9. Reduce the input level until the ‘OVR’ LED
just turns off.
10. From the Wavevision 4 pull-down menu
select “Acquire” and then samples. The
system will then capture the input waveform
and display the results in the time domain.
11. For FFT Analysis click the FFT Tab.
4.0 Functional Description
The ADC081500 Development Board schematic
is shown in Section 7.0.
4.1 Input circuitry
The input signal(s) to be digitized should be
applied to the front panel SMA connectors
labeled “I CH.” and “Q CH.”. These 50 Ohm
inputs are intended to accept a low-noise sine
wave signals. To accurately evaluate the
dynamic performance of this converter, the input
test signals will have to be passed through a
high-quality bandpass filter with at least 10-bit
equivalent noise and distortion characteristics.
This evaluation board as delivered is set up for
operation with two single-ended analog inputs,
which are converted to differential signals on
board.
Signal transformer T2, is connected as a balun,
and provides the single-ended to differential
conversion. The differential PCB traces to the
ADC analog input pins have a characteristic
differential impedance of 100 Ohms.
No scope or other test equipment should be
connected anywhere in the signal path while
gathering data.
4.2 ADC reference
The ADC081500 has an internal reference that
can not be adjusted. However, the Full-Scale
(differential) Range may adjusted with the
Software Control Panel Refer to Section 9.0 for
more information
4.3 ADC clock
The ADC clock is supplied on board and is fixed
at 1.5GHz. An external clock signal may be
applied to the ADC through the SMA Connector
labeled “CLOCK” on the front panel. The baluntransformer (T1) converts the single ended clock
source to a differential signal to drive the ADC
clock pins
Note that it is very important that the ADC clock
should be as free of jitter as possible or the
apparent SNR of the ADC081500 will be
compromised.
4.4 Digital Data Output
The digital output data from the ADC081500 is
connected to a Xilinx 4 FPGA. Up to 4K Bytes of
data can be stored and then uploaded over the
USB interface to the Wavevision 4 software. The
FPGA logic usage is low allowing further code to
be written and tested for product development.
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4.5 Power Requirements
The power supply requirement for the
ADC081500 Evaluation Board is 12V at 800mA.
Most of the regulators on board are switching
regulators for increased power efficiency.
The board typically draws around 500mA but it
is always good practice to have extra power
reserve in the power supply over the typical
power requirements.
A Universal 100-240V AC input to 12V DC Brick
Power Supply is included with the development
board.
4.6 Power Supply Connections
Power to this board is supplied through the
power connector on the rear panel. It is advised
that only the supplied PSU is used with this
board.
The ADC081500 supply voltage has been set to
1.9V, ±50 mV.
5.0 Obtaining Best Results
Obtaining the best results with any ADC
requires both good circuit techniques and a
good PC board layout. For layout information for
this product please contact you nearest National
Semiconductor representative
5.1 Clock Jitter
When any circuitry is added after a signal
source, some jitter is almost always added to
that signal. Jitter in a clock signal, depending
upon how bad it is, can degrade dynamic
performance. We can see the effects of jitter in
the frequency domain (FFT) as "leakage" or
"spreading" around the input frequency, as seen
in Figure 2a. Compare this with the more
desirable plot of Figure 2b. Note that all dynamic
performance parameters (shown to the right of
the FFT) are improved by eliminating clock jitter.
.
Figure 2a. Jitter causes a spreading around the input
signal, as well as undesirable signal spurs.
Figure 2b. Eliminating or minimizing clock jitter results in
a more desirable FFT that is more representative of how
the ADC actually performs.
6.0 Evaluation Board
Specifications
Board Size: 168mm x 100mm
Power Requirements: +12V, 800mA
Clock Frequency Range : 200 MHz to 1.5 GHz
Analog Input Range (AC Coupled) 30MHz to 1800MHz
Nominal Analog Input Voltage: 560 mV P-P to 870 mV P-P
Impedance: 50 Ohms
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7.0 Schematic Drawing ADC081500DEV – Onboard Clock (VCO + PLL)
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7.1 Schematic Drawing ADC081500DEV – Analog Inputs (I,Q) & Digital Trigger Input
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7.2 Schematic Drawing ADC081500DEV – ADC connected to Virtex4 FPGA
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7.3 Schematic Drawing ADC081500DEV – USB Interface
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