Linear Technology LTM9004 User manual

DC1513
1
DESCRIPTION
Demonstration circuit DC1513 is an evaluation board
featuring Linear Technology Corporation’s LTM9 4 14-
Bit Direct Conversion Receiver Subsystem. DC1513
demonstrates good circuit layout techniques and rec-
ommended external circuitry for optimal system per-
formance.
DC1513 comes with Linear Technology’s 14-bit
LTM9 4 receiver subsystem installed. The board in-
cludes output CMOS buffers. DC1513 plugs into the
DC89 Data Acquisition demo board 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. Call
the LTC factory.
L , LTC, LTM, LT, Burst Mode, OPTI-LOOP, Over-The-Top and PolyPhase are registered
trademarks of Linear Technology Corporation. Adaptive Power, C-Load, DirectSense, Easy
Drive, FilterCAD, Hot Swap, LinearView, µModule, Micropower SwitcherCAD, Multimode
Dimming, No Latency ∆Σ, No Latency Delta-Sigma, No R
SENSE
, Operational Filter, PanelProtect,
PowerPath, PowerSOT, SmartStart, SoftSpan, Stage Shedding, SwitcherCAD, ThinSOT,
UltraFast and VLDO are trademarks of Linear Technology Corporation. Other product names
may be trademarks of the companies that manufacture the products.
QUICK START PROCEDURE
Validating the performance of the LTM9 4 is simple
with DC1513, 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 two supply voltages for the
DC1513. 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 .5 Amp @ 5. VDC, and 1 Amp
@ 3. VDC.
2. Provide an encode clock to the ADC via SMA con-
nector 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.
Table 1: DC151 Connectors and Jumpers
REFERENCE FUNCTION
J3 (SHDN) Enables/disables the ADC. Default is ON.
J4 (MODE) Output Format and Clock Duty Stabilizer pin.
Default is VDD.
J5 (SHDN_AMP) Enables/disables the Amplifers. Default is ON.
J6 (LO) Board LO Signal Input. Impedance-matched to
5 Ω for use with lab signal generators.
J7 (CLK) Board Clock Input. Impedance-matched to
5 Ω. Drive with a low-phase-noise clock oscil-
lator or filtered sine wave signal source.
J8 (MIXER
ENABLE)
Enables/disables the RF mixer. Default is ON.
J11 (RF) Board RF Signal Input. Impedance-matched to
5 Ω for use with lab signal generators.
TP1 (SENSE_I) Reference input to adjust the full-scale range of
the DC1513, I Channel. Default is VDD.
TP2 (GND) DC ground.
TP4 (GND) DC ground.
TP5 (+3V) DC Supply input (3VDC).
TP7 (+5V) DC Supply input (5VDC).
TP8 (GND) DC ground.
TP12 (SENSE_Q) Reference input to adjust the full-scale range of
the DC1513, Q Channel. Default is VDD.
. Apply an RF input signal to the board. For best
results, use a low distortion, low noise signal
DEMO
CIRCUIT
DC
1513
QUICK START GUIDE
LTM9004 14 Bit D
irect
Conver ion Receiver Sub y
tem

DC1513
2
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 demo circuit
DC89 B, a USB cable, a Windows computer, and
Linear Technology’s PScope data processing soft-
ware.
Figure 1. Proper Measurement Equipment Setup
OTHER BOARD CIRCUITRY
Device U1 is an EEPROM device that is used by the PScope software to identify the board and apply the correct set-
tings for the data collection.
Signal
Generator
HP 8644B or equiv.
RF Signal Ge
n
erator
(HP 8644B) or other
low phase noise
clock source (e.g. DC1216)
Power Supply
(5. V @ .5A, 3. V @ 1. A)
To DC
89 B
BPF
NOTE.
Even a high
-
quali
ty signal
synthesizer will still have noise and
harmonics that should be attenuated
with a low-pass or band-pass filter. For
good-quality high order filters, see TTE,
Lark Engineering, or equivalent.
BPF
BPF
Signal
Generator
HP 8644B or equiv.

DC1513
3
USING PSCOPE SOFTWARE
PScope, downloadable from Linear Technology’s website http://www.linear.com/, processes data from the DC89 B
FastDAACS board and displays FFT and signal analysis information on the computer screen.
The on-board EEPROM U1 should enable automatic board detection and auto-configuration of the software, but if the
user wishes to change the settings, they can easily do so.
From the Configure menu in the toolbar, uncheck “Autodetect Device”. The default settings for DC1513 are shown in
Figure 2.
Figure 2. Entering the correct device information for your ADC. Select the correct parameters for the DC151 . Under normal conditions,
PScope should automatically recognize the board and adjust the software settings accordingly.

DC1513
4
Figure . Schematic.