Linear Technology DC1398 Quick Start Manual

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DESCRIPTION
Demonstration circuit 1398 is an evaluation board featur-
ing Linear Technology Corporation's LTM9001 16-bit
Receiver Subsystem. DC1398 demonstrates good circuit
layout techniques and recommended external circuitry
for optimal system performance.
DC1398 comes with Linear Technology's 16-bit
LTM9001 amplifier/ADC subsystem installed. The board
includes a wideband input transformer (for evaluation
with a single-ended RF signal generator) and output
QUICK START PROCEDURE
Validating the performance of the LTM9001 is simple
with DC1398, and requires only an input source, 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 three supply voltages for the LTM9001.
The entire board and all components share a com-
mon ground. The power supply should still be a low-
noise lab power supply capable of supplying at least
1 Amp.
2. Provide an encode clock to the ADC via SMA con-
nector J3. Use a low-phase-noise clock source such
as a filtered RF signal generator or a high-quality
clock oscillator. Obtain DC1216 for a low-phase-
noise ADC clock source that can plug directly into
DC1398.
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: DC1398 Connectors and Jumpers
REFERENCE FUNCTION
J1 (AIN-) Differential Board Input. Normally not con-
nected. See text for differential-input evalua-
DEMO CIRCUIT 1398
QUICK START GUIDE
LTM9001 16-bit High
Performance ADC Drivers
CMOS buffers. DC1398 plugs into the DC890 Data Ac-
quisition demo board and the output can be easily ana-
lyzed 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
tion methods.
J2 (AIN+) Board Signal Input. Impedance-matched to
50Ω for use with lab signal generators.
J3 (ENC) Board Clock Input. Impedance-matched to
50Ω. Drive with a low-phase-noise clock oscil-
lator or filtered sine wave signal source.
E1 (EXT REF) Reference input to adjust the full-scale range of
the LTM9001. Connects to the SENSE pin; by
default, tied to VDD for internal reference.
E2 (VS) DC Supply input (3.8 to 6VDC).
E3 (GND) DC ground.
JP1 (PGA_GAIN) Selects the input range of LTM9001. Default is
LOW (low PGA gain, larger input range)
JP2 (RAND) Output Randomizer. Default is NORM.
JP3 (ADC_SHDN) Enables the LTM9001 ADC. Default is NORM.
JP4 (DITH) ADC Internal Dither. Default is OFF.
JP5 (AMP_EN) Enables the LTM9001 amplifier. Default is EN.
3. Apply an input signal to the board. DC1398 allows
great flexibility in applying input signals (see the sec-
tion on Applying Input Signals). For best results, use a
low distortion, low noise signal generator with suffi-
cient filtering to avoid degrading the performance of
the amplifier and ADC.
4. Observe the ADC output with demo circuit DC890, a
USB cable, a Windows computer, and Linear Tech-
nology's Pscope
DC1250
data processing software.
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