9.0 Evaluation Board Bill of Materials...........................................................................................10
A1.0 Operating in the Computer Mode.........................................................................................12
A2.0 Summary Tables of Test Points and Connectors ................................................................12
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1.0 Introduction
These Design Kits (each consisting of an Evaluation
Board, National's WaveVision software and this manual)
is designed to ease evaluation and design-in of Nationals
ADC12040, ADC12010, ADC12020, or ADC12L063 12bit Analog-to-Digital Converter, which operate at speeds
up to 40 Msps, 10 Msps, 20 Msps and 62 Msps,
respectively. Further reference in this manual to the
ADC12040 is meant to also include the ADC12010,
ADC12020 and the ADC12L063, unless otherwise
specified or implied. Note that the maximum sample rate
capability of the WaveVision system in the Computer or
Automatic mode is 60 Msps.
The WaveVision software can be operated under
Microsoft Windows. The signal at the Analog Input is
digitized and can be captured and displayed on a PC
monitor as a dynamic waveform. The digitized output is
also available at Euro connector J2.
The software can perform an FFT on the captured data
upon command and, in addition to a frequency domain
plot, shows dynamic performance in the form of SNR,
SINAD, THD and SFDR.
A prototype area is available for building customized
circuitry.
The evaluation board can be used in either of two modes.
In the Manual mode suitable test equipment can be used
with the board to evaluate the ADC12040 performance.
In the Computer mode evaluation is simplified by
connecting the board to the WaveVision Digital Interface
Board (order number WAVEVSN BRD 3.0), which is
connected to a personal computer through a serial
communication port and running WaveVision software,
operating under Microsoft Windows. Or use WAVEVSN
BRD 4.0 when available on National's web site. Use the
WaveVision2 program (WAVEVSN2.EXE) or use
WaveVision 4.0 when available on National's web site.
The signal at the Analog Input to the board is digitized
and is available at pins B16 through B21 and C16
through C21 of J2. Pins A16 through A21 of J2 are
ground pins.
Provision is made for adjustment of the Reference
Voltage, V
REF
, with VR1.
2.0 Board Assembly
The ADC12040 Evaluation Board may come preassembled or as a bare board that must be assembled.
Refer to the Bill of Materials for a description of
components, to Figure 1 for major component placement
and to Figure 6 for the Evaluation Board schematic.
A breadboard area is provided for building customized
circuitry. For best performance, keep circuitry neat and
arrange components to provide short, direct connections.
JS0 & JS1
Detail
Standard
TP1
V
REF
JP3 & JP4
Detail
J1 Input
Position
JP2
Detail
Default
Position
JS3
Detail
Standard
VR1
Ref. Adj.
TP5
SIGNAL
INPUT
TP3
Vin+
JS1JS0
VR1
VREF
TP1
TP5
SIG IN
J3 J1
Analog
TP4
Vin-
Input
JP2
TP10
CLK
SELECT
RP2 RP1
U1
Vin+
Vin-
TP3
TP4
TP6
PWR DWN
T1
L1
JP3
MIX
JP4
SELECT
J1
J3
Analog
Input
TP20
OE-
ADC CLK
-V
-V
TP10+VTP8
CLK SEL
JP2
JS3
VDO
TP2
L2
L10
TP7
L3
Y1
L4
+5V
TP9
D1
L5
TP6
PWR
DWN
Figure 1. Component and Test Point Locations
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TP8
+V
POWER CONNECTOR
P1
TP9
+5V
DR VD
ADC CLK
+V
GND
+5V
-V
Power
TP2
TP7
P1
Page 4
3.0 Quick Start
Note: To develop the ADC clock, the Digital Interface
Board divides its on-board clock. In doing so, jitter is
introduced to the ADC clock which degrades the
observed performance of the ADC12040. See Section
6.0 Obtaining Best Results for an explanation of this
phenomenon and how to avoid it.
Refer to Figure 1 for locations of test points and major
components. For Stand-Alone operation:
1.Install an appropriate crystal into socket Y1. While
the oscillator may be soldered to the board, using a
socket will allow you to easily change clock
frequencies.
2.Connect a clean power supply to Power Connector
P1. Supply +5V at pin 3 of P1 to supply the Digital
Interface board. Supply +3.3V to pin 1 for the
ADC12L063, or +5V to pin 1 for the ADC12010,
ADC12020 and the ADC12040. Pin 2 is ground.
3.Use VR1 to set the reference voltage (V
is 2.0V for the ADC12040, ADC12010, or
ADC12020, or to 1.0V for the ADC12L063. V
can be measured at TP1.
4.To use the crystal oscillator located at Y1 to clock
the ADC, connect the jumper at JP2 to pins 2 and 3.
This is the default position. The ADC clock signal
may be monitored at TP7. Because of clock
isolation resistor R12 and the scope probe
capacitance, the clock signal at TP7 will appear
integrated.
5.Connect the jumper at JP3 between pins 1 and 2,
and the jumper at JP4 to pins 1 and 2 to select input
J1 only. This is the default position.
6.Connect a signal of 1.4 V
ADC12040, ADC12010 or the ADC12020, or 0.7
V
for the ADC12L063 from a 50-Ohm source to
P-P
Analog Input BNC J1. The ADC input signal can be
observed at TP5. Because of isolation resistor R18
and the scope probe capacitance, the input signal at
TP5 may not have the same frequency response as
the ADC input. Be sure to use a bandpass filter
before the Evaluation Board.
7.Adjust the input signal amplitude as needed to
ensure that the signals at TP3 and TP4 remains
within the valid signal range of 0V to V
8.The digitized signal is available at pins B16 through
B21 and C16 through C21 of J2. See board
schematic of Figure 6.
For Computer Mode operation:
NB: Be sure to read section 6.1 before using this
board in the Computer Mode.
1.Connect the evaluation board to the Digital Interface
Board. See the Digital Interface Board Manual for
operation of that board.
amplitude for the
P-P
REF
REF
), which
REF
.
2.Perform steps 2 and 3 of stand alone quick start,,
above.
3.Use of the crystal oscillator located at Y1 is
recommended to clock the ADC. To do so, connect
the jumper at JP2 to pins 2 and 3. This is the default
position. The ADC clock signal may be monitored at
TP7. Because of clock isolation resistor R12 and the
scope probe capacitance, the clock signal at TP7
will appear integrated.
4.Perform steps 5 through 7 of the Stand-Alone quick
start, above.
5.See the Digital Interface Board Manual for
instructions for setting the ADC clock frequency and
for gathering data.
4.0 Functional Description
The ADC12040 Evaluation Board schematic is shown in
Figure 6.
4.1 Input (signal conditioning) circuitry
The input signal to be digitized should be applied to BNC
connector J1. This 50 Ohm input is intended to accept a
low-noise sine wave signal of 2V peak-to-peak amplitude
for the ADC12040, ADC12010 and ADC12020 or 1V
peak-to-peak for the ADC12L063. To accurately evaluate
the dynamic performance of these converters, the input
test signal will have to be passed through a high-quality
bandpass filter with at least 14-bit equivalent noise and
distortion characteristics.
Signal transformer T1 provides single-ended to
differential conversion. The common mode voltage at the
ADC input is equal to the reference voltage of the ADC.
No scope or other test equipment should be connected to
TP3 or to TP4 while gathering data.
This evaluation board is capable of accommodating a
single input or two different inputs. These inputs are NOT
differential in nature, but are intended to mix two different
signals before presenting them to the ADC.
NOTE: If input frequency components above 30
MHz are required, remove capacitor C7 at the ADC
differential input pins.
4.1.1 Single Input
To evaluate the ADC12040 with a single input, connect
jumpers JP3 and JP4 in their default positions, as shows
in Figure 1. That is, short together pins 1 and 2 of JP3
and of JP4. Doing so provides a 50-Ohm input at J1. No
connection should be made to J3. This configuration is
appropriate for evaluation of dynamic performance
parameters.
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4.1.2 Dual Input
To look at intermodulation performance, moving shorting
jumpers of JP3 and JP4 to pins 2 and 3 of JP3. Connect
different signals to J1 and J3 from 50-Ohm sources.
When looking at the ADC output with two different signals
at the input, the dynamic performance parameters (SNR,
SINAD, THD and SFDR) are meaningless. With two input
signals we are looking for any spurs in the frequency
domain plot (FFT). The simple method used here to mix
two signals is not adequate to completely evaluate IMD of
these converters. Consequently, the actual IMD
performance of the A/D converter is better than would be
indicated by using this method. Most high speed ADCs
exhibit high spurious content under these conditions
unless the total input swing is very low compared with full
scale.
As mentioned in Section 5.0, it is important to use a
bandpass filter at BNC J1 (and BNC J3, if this input is
used) to ensure the quality of the signal presented to the
ADC and to get meaningful test results.
4.2 ADC reference circuitry
An adjustable reference circuit is provided on the board.
The simple circuit here is not temperature stable and is
not recommended for your final design solution. When
using the resistor values shown in Figure 1, the reference
circuit will generate a nominal reference voltage in the
range of 0 to 2.4 Volts for the ADC12040, ADC12010 and
ADC12020 or 0 to 1.2 Volts for the ADC12L063. The
ADC12040, ADC12010 and ADC12020 are specified to
operate with V
nominal value of 2.0V while the ADC12L063 is specified
to operate with V
nominal value of 1.0V. The reference voltage can be
monitored at test point TP1 and is set with VR1.
in the range of 1.0 to 2.4 V, with a
REF
in the range of 0.8 to 1.2 V, with a
REF
4.3 ADC clock circuit
The clock signal applied to the ADC is selected with
jumper JP2. A standard crystal oscillator can be installed
at Y1 and selected with jumper JP2 pins 2 and 3 shorted
together. To use a different clock source, connect the
signal to pin B23 of J2 and select pins 1 and 2 of jumper
JP2. The ADC clock frequency can be monitored at test
point TP7. R13 and C13 are used for high frequency
termination of the clock line. In the Computer mode of
operation using the Digital Interface Board, JP2 can have
pins 1 and 2 shorted together to use the clock from the
Digital Interface Board, but this is not recommended, as
discussed in Section 6.1.
Note that any external clock source must have
TTL/CMOS levels. Also, if using the Digital Interface
Board from National Semiconductor to capture data, the
oscillator at Y1 should be removed, the external clock
signal supplied at pin 3 of that socket and pins 2 and 3 of
JP2 should be selected. Additionally, the clock frequency
must be the same as that provided from the Digital
Interface Board.
See Section 6.1 for information on capturing data with a
clock that is not synchronized to the clock of the Digital
Interface Board.
4.5 Digital Data Output
The digital output data from the ADC12040 is available at
the 96-pin Euro connector J2. Series resistors RP1 and
RP2 isolate the ADC from the load circuit to reduce noise
coupling into the ADC.
4.5 Power Supply Connections
Power to this board is supplied through power connector
P1. The only supply needed is +5V at pin 1 for the
ADC12040, ADC12010 or the ADC12020, or +3.3V at pin
1 for the ADC12L063, plus ground at pin 2 for either. Any
circuitry you breadboard may need a negative voltage at
the -V supply pin 4.
When using the ADC12040 Evaluation Board with the
Digital Interface Board, a 5V logic power supply for the
interface board is needed at pin 3 of P1. This supply
voltage is passed through J2 to the Digital Interface
Board.
The supply voltages are protected by shunt diodes and
can be measured at TP8, TP9 and TP10. If a
breadboarded circuit requires voltages greater than 5V,
they will have to be separately provided by the user.
4.6 Power Requirements
Voltage and current requirements for the ADC12040
Evaluation Board mode are:
For the ADC12040, ADC12010 and the ADC12020:
•+5.0V at 100 mA [+V]
•+5.0V at 30 mA (1A when connected to the Digital
Interface Board) [+5V].
For the ADC12L063:
•+3.3V at 120 mA [+V]
•+5.0V at 30 mA (1A when connected to the Digital
Interface Board) [+5V].
There is no need for a negative supply for either ADC,
unless it may be needed for the breadboard area.
5.0 Installing the ADC12040 Evaluation Board
The evaluation board requires power supplies as
described in Section 4.6. An appropriate signal source
should be connected to the Analog Input BNC J1. When
evaluating dynamic performance, an appropriate signal
generator (such as the HP8644B, HP8662A or the R&S
SME-03) with 50 Ohm source impedance should be
connected to the Analog Input BNC J1 and/or J3 through
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an appropriate bandpass filter as even the best signal
generator available can not produce a signal pure enough
to evaluate the dynamic performance of an ADC.
If this board is used in conjunction with the Digital
Interface Board and WaveVision software, a cable with a
DB-9 connector must be connected between the Digital
Interface Board and the host computer when using
WAVEVSN BRD 3.0 Digital Interface Board. See the
Digital Interface Board manual for details.
6.0 Obtaining Best Results
Obtaining the best results with any ADC requires both
good circuit techniques and a good PC board layout. The
layout is taken care of with the design of this evaluation
board.
6.1 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.
ADC12010 evaluation board, a 20 MHz oscillator for
the ADC12020 evaluation board, or a 60 MHz on the
ADC12L063 evaluation board).
3.Connect the jumper at JP2 to pins 2 and 3 (default
position). This selects the crystal oscillator located
at Y1 on the evaluation board (rather than the
divided oscillator signal on the Digital Interface
Board) to clock the ADC.
Because the divided signal from the Digital Interface
Board and the oscillator at Y1 are not synchronized, bad
data will sometimes be taken because we are latching
data when the outputs are in transition. This data might
be as you see in Figure 3 or Figure 4.
To develop the ADC clock, WAVEVISON BRD 3.0 Digital
Interface Board divides its on-board clock to provide the
ADC clock. In doing so, jitter is introduced to the ADC
clock, degrading the observed performance of the ADC.
The amount of jitter produced by this evaluation system
is acceptable for relatively low input frequencies (below
about 5 MHz). But at higher frequencies and resolutions
this jitter can make it appear as though the ADC does not
perform well.
For many applications the results seen will be completely
acceptable. However, if it is desired to observe the best
results possible from the ADC, you should not use the
Digital Interface Board to capture data OR you should do
the following when using the Digital Interface Board:
1.Use an 80 MHz oscillator on the Digital Interface
Board (120 MHz for the ADC12L063) with the DIP
switches on that board set to divide the oscillator
frequency by the appropriate amount. See the
Digital Interface Board manual for details on setting
the divide ratio. The goal here is to have the divided
clock from the Digital Interface Board be the same
frequency as the oscillator on the ADC12040
Evaluation Board.
2.Use a 40 MHz oscillator on the ADC12040
evaluation board, a 10 MHz oscillator for the
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.
The problem of Figure 3 is obvious, but it is not as easy
to see the problem in Figure 4, where the only thing we
see is small excursions beyond the normal envelope.
Compare Figure 3 and Figure 4 with Figure 5.
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If your data capture results in something similar to what is
shown here in Figure 3 or in Figure 4, take another
sample. It may take a few trials to get good data.
Figure 3. Poor data capture resulting from trying to capture
data while the ADC outputs are in transition
6.2 Coherent Sampling
Artifacts can result when we perform an FFT on a
digitized waveform, producing inconsistent results when
testing repeatedly. The presence of these artifacts means
that the ADC under test may perform better than the
measurements would indicate.
We can eliminate the need for windowing and get more
consistent results if we observe the proper ratios between
the input and sampling frequencies. We call this coherentsampling. Coherent sampling greatly increases the
spectral resolution of the FFT, allowing us to more
accurately evaluate the spectral response of the A/D
converter. When we do this, however, we must be sure
that the input signal has high spectral purity and stability
and that the sampling clock signal is extremely stable
with minimal jitter.
Figure 4 Marginal data capture that results from trying to
capture data that is near but not right at the point where the
ADC outputs are in transition.
Figure 5. Normal data capture.
Coherent sampling of a periodic waveform occurs when a
prime integer number of cycles exists in the sample
window. The relationship between the number of cycles
sampled (CY), the number of samples taken (SS), the
signal input frequency (fin) and the sample rate (fs), for
coherent sampling, is
f
CY
in
=
f
SS
s
CY, the number of cycles in the data record, must be a
prime integer number and SS, the number of samples in
the data record, must be a factor of 2 integer.
Further, fin (signal input frequency) and fs (sampling rate)
should be locked to each other so that the relationship
between the two frequencies is exact. Locking the two
signal sources to each other also causeswhatever
sample-to-sample clock edge timing variation (jitter) that
is present in the two signals to cancel each other.
Windowing (an FFT Option under WaveVision) should be
turned off for coherent sampling.
7.0 Evaluation Board Specifications
Board Size:6.5" x 3.5" (16.5 cm x 8.9 cm)
Power Requirements:+5.0V, 100 mA (ADC12040 /
Clock Frequency Range: 1.0 MHz to 40 MHz or 60 MHz
Analog Input
40-TP10not populatedn/a
411T1Signal TransformerMiniCircuits type T4-6T
421U1ADC12010CIVY, ADC12020CIVY,
431Y110 MHz Oscillator for ADC12010
441
451
462--Jumpers for JP2 & JS3DigiKey # S9001-ND
TP7, TP8, TP9, TP20
--
--
ADC12L063)
33, 5% (47Ω for ADC12010 / 12020)
Breakable HeaderDigiKey # S1012-36-ND
ADC12040CIVY or ADC12L063CIVY
20 MHz Oscillator for ADC12020
40 MHz Oscillator for ADC12040
60 MHz Oscillator for ADC12L063
6-pin Socket for TransformerDigiKey # AE8906-ND
4-Pin full-size oscillator socketDigiKey # A462-ND
Various
Type 1206
National Semiconductor
Pletronics #P1145-3SD-10.0M
Pletronics #P1145-3SD-20.0M
Pletronics #P1145-3SD-40.00M
Pletronics #P1145-3SD-60.0M or
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APPENDIX
A1.0 Operating in the Computer Mode
The ADC12040 Evaluation Board is compatible with the WaveVision Digital Interface Board and WaveVision software.
When connected to the Digital Interface Board, data capture is easily controlled from a personal computer operating in
the Windows environment. The data samples that are captured can be observed on the PC video monitor in the time and
frequency domains. The FFT analysis of the captured data yields insight into system noise and distortion sources and
estimates of ADC dynamic performance such as SINAD, SNR and THD.
See the Digital Interface Board manual for more information.
A2.0 Summary Tables of Test Points and Connectors
Test Points on the ADC12040 Evaluation Board
TP 1ADC Reference Voltage
TP 2ADC output driver supply voltage
TP 3Positive input signal to the ADC (Vin+)
TP 4Negative input signal to the ADC (Vin-)
TP 5Signal Input test point
TP 6Power Down (active high) input
TP 7ADC clock frequency monitor
TP 8+5V power supply for ADC12040 / 12010 / 12020 or +3.3V for ADC12L063
TP 9+5V power supply for the Digital Interface Board, if used
TP 10Optional negative power supply for breadboard area
TP 20Output Enable input. Pull high to disable the outputs
P1 Connector - Power Supply Connections
J1-1+VPositive Power Supply (+5V for ADC12040/12010/12020 or +3.3V for ADC12L063)
J1-2GNDPower Supply Ground
J1-3+5V+5.0V Logic Power Supply for Digital Interface Board
J1-4-VOptional Negative Power Supply for Breadboard Area
JP2 Jumper - ADC Clock selection jumper settings
Connect 1-2Use Clock signal from J2 pin B23
Connect 2-3Use crystal oscillator Y1
JP3 Jumper - ADC Input Select
Connect 1-2Use single J1 Input
Connect 2-3Mix J1 & J3 Inputs (must also have JP4 pins 1 & 2 shorted)
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JP4 Jumper - ADC Input Select
Connect 1-2Select input J1 only
Connect 2-3Select mixed J1 & J3 Inputs (must also have JP3 pins 2 & 3 shorted)
J2 Connector - ADC Data Outputs - Connection to WaveVision Digital Interface Board
(+5V Logic Power Supply to Digital Interface Board )
Reserved, powerA29, B29, C29
Reserved, powerA32, B32, C32
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BY USING THIS PRODUCT, YOU ARE AGREEING TO BE BOUND BY THE TERMS AND CONDITIONS OF
NATIONAL SEMICONDUCTOR'S END USER LICENSE AGREEMENT. DO NOT USE THIS PRODUCT UNTIL YOU
HAVE READ AND AGREED TO THE TERMS AND CONDITIONS OF THAT AGREEMENT. IF YOU DO NOT AGREE
WITH THEM, CONTACT THE VENDOR WITHIN TEN (10) DAYS OF RECEIPT FOR INSTRUCTIONS ON RETURN OF
THE UNUSED PRODUCT FOR A REFUND OF THE PURCHASE PRICE PAID, IF ANY.
The ADC12040/ADC12010/ADC12020/ADC12L063 Evaluation Boards are intended for product evaluation purposes only
and are not intended for resale to end consumers, is not authorized for such use and is not designed for compliance with
European EMC Directive 89/336/EEC, or for compliance with any other electromagnetic compatibility requirements.
National Semiconductor Corporation does not assume any responsibility for use of any circuitry or software supplied or
described. No circuit patent licenses are implied.
LIFE SUPPORT POLICY
NATIONAL'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL
SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform, when properly used in
accordance with instructions for use provided in the
2. A critical component is any component in a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
labeling, can be reasonably expected to result in a
significant injury to the user.
National does not assume any responsibility for any circuitry described, no circuit patent licenses are implied and National reserves the right
at any time without notice to change said circuitry and specifications.
12http://www.national.com
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