Demonstration circuit 1281A supports a family of 16bit 160Msps/180Msps/185Msps ADCs. Each assem-
®
bly features one of the following devices: LTC
2209,
LTC2209#3BC, or LTC2209#3CD high speed, high dynamic
range ADC.
Other members of this family include the LTC2208 which
is a 130Msps 16-bit version of this device. The LTC2208 is
supported on the DC854 (CMOS) and the DC996 (LVDS).
Lower speed, single-ended clock versions are also supported on the DC918 and DC919.
Table 1. DC1281A Variants
DC1281A VARIANTSADC PART NUMBERRESOLUTIONMAXIMUM SAMPLE RATEINPUT FREQUENCYSUPPLY VOLTAGE
1281A-ALTC220916-Bit160Msps1MHz to 80MHz3.3V
1281A-BLTC220916-Bit160Msps80MHz to 160MHz 3.3V
1281A-ELTC2209#3BCPBF16-Bit180Msps1MHz to 80MHz3.6V
1281A-FLTC2209#3BCPBF16-Bit180Msps80MHz to 160MHz 3.6V
1281A-GLTC2209#3CDPBF16-Bit185Msps1MHz to 80MHz3.6V
1281A-HLTC2209#3CDPBF16-Bit185Msps80MHz to 160MHz 3.6V
Several versions of the 1281A demo board supporting
the LTC2209 16-bit series of A/D converters are listed in
Table 1. Depending on the required resolution, sample rate
and input frequency, the DC1281A is supplied with the
appropriate ADC and with an optimized input circuit. The
circuitry on the analog inputs is optimized for analog input
frequencies below 80MHz or from 80MHz to 160MHz. For
higher input frequencies, contact the factory for support.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks; QuikEval
and PScope are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
PERFORMANCE SUMMARY
PARAMETERCONDITIONVALUE
Supply Voltage – LTC2209Depending on Sampling Rate and the A/D Converter Provided, This Supply Must
Supply Voltage – LTC2209#3BC
and LTC2209#3CD
Analog Input RangeDepending on PGA Pin Voltage1.5V
Logic Input VoltagesMinimum Logic High
Convert Clock Level50Ω Source Impedance, AC-Coupled or Ground Referenced (Convert Clock Input Is
ResolutionSee Table 1
Input Frequency RangeSee Table 1
SFDRSee Applicable Data Sheet
SNRSee Applicable Data Sheet
Provide Up to 700mA.
Depending on Sampling Rate and the A/D Converter Provided, This Supply Must
Provide Up to 700mA.
Maximum Logic Low
Minimum Logic Levels (100Ω Load)
See Table 1
Capacitor Coupled on Board and Terminated with 50Ω).
(TA = 25°C)
Optimized for 3.3V
[3.15V⇔3.45V min/max]
Optimized for 3.6V
[3.5V⇔3.78V min/max]
to 2.25V
P-P
2V
0.8V
350mV/2.1V Common Mode
247mV/2.1V Common Mode
⇔2.5V
2V
P-P
Square wave
P-P
Sine Wave or
P-P
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DEMO MANUAL DC1281A
QUICK START PROCEDURE
Demonstration circuit 1281A is easy to set up to evaluate
the performance of the LTC2209 A/D converters. Refer to
Figure 1 for proper measurement equipment setup and
follow the procedure below:
Setup
If a DC890 QuikEval™ II Data Acquisition and Collection
System was supplied with the DC1281A demonstration
circuit, follow the DC890 Quick Start Guide to install the
required software and for connecting the DC890 to the
DC1281A and to a PC.
3.6V OR 3.3V
RAND
PGA
DC1281A Demonstration Circuit Board Jumpers
The DC1281A demonstration circuit board should have
the following jumper settings as default: (as per Figure 1):
J2: Mode (VCC) 2’s Complement DCS Off
J3: SHDN: (Run) Dither (Off)
J4: RAND (Off) PGA 1x
J9: Unused Power Connector
MODE
ANALOG
INPUT
DITHER
SHDN
ENCODE CLOCK
Figure 1. DC1281A Setup (Zoom for Detail)
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QUICK START PROCEDURE
DEMO MANUAL DC1281A
Applying Power and Signals to the DC996
Demonstration Circuit
If a DC890 is used to acquire data from the DC1281A, the
DC890 must first be connected to a powered USB port
or provided an external 6V to 9V before applying 3.3V or
3.6V across the pins marked +3.3V and PWR GND on the
DC1281A. The LTC2209#3BC and LTC2209#3CD require
3.6V for proper operation. The DC1281A demonstration
circuit requires up to 700mA depending on the sampling
rate and the A/D converter supplied.
The DC890 data collection board is powered by the USB
cable and does not require an external power supply unless
it must be connected to the PC through an unpowered hub
in which case it must be supplied an external 6V to 9V on
turrets G7(+) and G1(–) or the adjacent 2.1mm power jack.
Analog Input Network
For optimal distortion and noise performance the RC
network on the analog inputs may need to be optimized
for different analog input frequencies. For input frequencies above 160MHz use demonstration circuit 1281A.
Other input networks may be more appropriate for input
frequencies less that 5MHz.
In almost all cases, filters will be required on both analog
input and encode clock to provide data sheet SNR.
The filters should be located close to the inputs to avoid
reflections from impedance discontinuities at the driven
end of a long transmission line. Most filters do not present
50Ω outside the passband. In some cases, 3dB to 10dB
pads may be required to obtain low distortion.
If your generator cannot deliver full-scale signals without
distortion, you may benefit from a medium power amplifier
based on a Gallium Arsenide Gain block prior to the final
filter. This is particularly true at higher frequencies where
IC-based operational amplifiers may be unable to deliver
the combination of low noise figure and High IP3 point
required. A high order filter can be used prior to this final
amplifier, and a relatively lower Q filter used between the
amplifier and the demo circuit.
Encode Clock
Note: This is not a logic-compatible input. It is terminated
with 50Ω. Apply an encode clock to the SMA connector
on the DC1281A demonstration circuit board marked
J7 ENCODE INPUT. This is a transformer-coupled input,
terminated on the secondary side in two steps, 100Ω at
the transformer with final termination at the ADC at 100Ω.
For the best noise performance, the ENCODE INPUT must
be driven with a very low jitter source. When using a sinusoidal generator, the amplitude should often be as large
as possible, up to 3V
on the clock and the analog input will improve the noise
performance by reducing the wideband noise power of the
signals. Data sheet FFT plots are taken with 10-pole LC
filters made by TTE (Los Angeles, CA) to suppress signal
generator harmonics, non-harmonically related spurs and
broadband noise. Low phase noise Agilent 8644B generators are used with TTE bandpass filters for both the clock
input and the analog input.
Apply the analog input signal of interest to the SMA connectors on the DC1281A demonstration circuit board marked
J5 ANALOG INPUT. These inputs are capacitive coupled to
Balun transformers ETC1-1-13, or directly coupled through
Flux-coupled transformers ETC1-1T.
An internally generated conversion clock output is available
on J1 which could be collected via a logic analyzer, or other
data collection system if populated with a SAMTEC MEC8150 type connector or collected by the DC890 QuikEvalII
Data Acquisition Board using PScope™ software.
Software
The DC890 is controlled by the PScope system software
provided or downloaded from the Linear Technology
website at
was provided, follow the DC890 Quick Start Guide and
the instructions below.
To start the data collection software if PScope.exe is installed (by default) in \Program Files\LTC\PScope\, double
click the PScope icon or bring up the run window under
the start menu and browse to the PScope directory and
select PScope.
http://www.linear.com/software/. If a DC890
or 15dBm. Using bandpass filters
P-P
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DEMO MANUAL DC1281A
QUICK START PROCEDURE
If the DC1281A demonstration circuit is properly connected
to the DC890, PScope should automatically detect the
DC1281A, and configure itself accordingly. If necessary
the procedure below explains how to manually configure
PScope.
Under the Configure menu, go to ADC Configuration....
Check the Config Manually box and use the following
configuration options, see Figure 2:
Manual configuration settings:
Bits: 16
Alignment: 16
FPGA Ld: LVDS
Channs: 1
Bipolar: Checked
Positive-Edge Clk: Checked
If everything is hooked up properly, powered and a suitable convert clock is present, clicking the Collect button
should result in time and frequency plots displayed in
the PScope window. Additional information and help for
PScope is available in the DC890 Quick Start Guide and in
the online help available within the PScope program itself.
Figure 2: ADC Configuration
PARTS LIST
ITEMQTYREFERENCEPART DESCRIPTIONMANUFACTURER/PART NUMBER
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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DEMO MANUAL DC1281A
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
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arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer.