Linear Technology LTM9003 Demo Manual

Description
Demonstration circuit DC1642A is an evaluation board fea-
turing Linear Technology Corporation's LTM
predistortion receiver subsystem. DC1642A demonstrates
good circuit layout techniques and recommended external
circuitry for optimal system performance.
DC1642A comes with Linear Technology's 12-bit LTM9003
receiver subsystem installed. The board includes output
LVDS buffers. DC1642A plugs into the DC890 data acqui-
quick start proceDure
Validating the performance of the LTM9003 is simple
with DC1642A, and requires only two input sources, a
clock source, a computer, and a lab power supply. Refer
to Figure 1 for proper board evaluation equipment setup
and follow the procedure below:
1. Connect the power supply as shown in Figure 1. There
are on-board low-noise voltage regulators that provide
the supply voltage for the DC1642A. The entire board
and all components share a common ground. The power
supply should still be a low-noise lab power supply
capable of supplying at least 1A.
2. Provide an encode clock to the ADC via SMA connector
J7. Use a low-phase-noise clock source such as a filtered
RF signal generator or a high-quality clock oscillator.
Note: Similar to having a noisy input, a high-jitter (phase
noise) encode clock will degrade the signal-to-noise ratio
(SNR) of the system.
orDer options
Table 1. DC1642A Variants
DC1624 VARIANTS
1624A-AA
1624A-AB
Arrow.com.
Downloaded from
9003 12-Bit
®
PART NUMBER SFDR
LTM9003A-AA 58.8dB
LTM9003A-AB 62.4dB
DEMO MANUAL DC1642A
12-Bit Digital Predistortion
Receiver Subsystem
sition demo board using an FT149 adapter card and the
output can be easily analyzed with Linear Technology's
PScope™ data processing software, which is available
for no charge on our website at http://www.linear.com.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, µModule, Linear Technology and the Linear logo are registered trademarks
and PScope is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
3. Apply an RF input signal to the board. For best results,
use a low distortion, low noise signal generator with
sufficient filtering to avoid degrading the performance
of the receiver.
4. Apply an LO input signal to the board. Note that the
difference in frequency between this signal and the RF
signal will be the IF frequency resulting at the IF filter
and ADC input.
5. Observe the ADC output with the FT149 adapter card
connected to the DC890, a USB cable, a Windows
computer, and Linear Technology's PScope data pro-
cessing software. Note that the DC890 will also require
an external 6V/1A power supply when receiving LVDS
outputs.
SUPPLY VOLTAGE
2.5V ADC, 3.3V Amplifier, 3.3V Mixer
2.5V ADC, 3.3V Amplifier, 5V Mixer
LTM9003
BANDPASS FILTER
184MHz Center, 125MHz Bandwidth
184MHz Center, 125MHz Bandwidth
dc1642af
1