DESCRIPTION
Demonstration circuit 1241 is an evaluation board
featuring
LTM9001 16-bit Receiver Subsystem. DC1241
demonstrates good circuit layout techniques and
recommended external circuitry for optimal system
performance.
DC1241 comes installed with one of Linear Tech-
nology’s 16-bit LTM9001 amplifier/ADC subsys-
tems. The board includes a wideband input trans-
former (for evaluation with a single-ended RF sig-
nal generator) and output LVDS buffers. The
LTM9001 is also capable of generating CMOS
QUICK START PROCEDURE
Validating the performance of the LTM9001 is sim-
ple with DC1241, 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 proce-
dure below:
1. Connect the power supply as shown in Figure 1.
2. Provide an encode clock to the ADC via SMA
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 common ground. The power supply
should still be a low-noise lab power supply ca-
pable of supplying at least 1 Amp.
connector 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 DC1241.
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.
Linear
Technology
16-BIT HIGH PERFORMANCE ADC DRIVERS
Corporation’s
outputs – for evaluation of the part with CMOS
outputs, obtain DC1250. DC1241 plugs into the
DC890 Data Acquisition demo board and the out-
put can be easily analyzed with Linear Technol-
ogy’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.
Table 1: DC1241 Connectors and Jumpers
3. Apply an input signal to the board. DC1241 al-
, LTC and LT are registered trademarks of Linear Technology Corporation.
lows great flexibility in applying input signals
REFERENCE
J1 (AIN-)
J2 (AIN+)
J3 (ENC)
E3 (EXT REF)
JP1 (AMP_EN)
JP2
(PGA_GAIN)
JP3 (RAND)
JP4
(ADC_SHDN)
JP5 (DITH)
LTM9001 16-bit Re-
DEMO CIRCUIT 1241
QUICK START GUIDE
ceiver Subsystem
FUNCTION
Differential Board Input. Normally not
connected. See text for differential-input
evaluation methods.
Board Signal Input. Impedance-matched
to 50Ω for use with lab signal generators.
Board Clock Input. Impedance-matched
to 50Ω. Drive with a low-phase-noise
clock oscillator or filtered sine wave signal
source.
Reference input to adjust the full-scale
range of the LTM9001. Connects to the
SENSE pin; by default, tied to VDD for
internal reference.
Enables the LTM9001 amplifier. Default is
EN.
Selects the input range of LTM9001. De-
fault is LOW (low PGA gain, larger input
range)
Output Randomizer. NORM is default.
Enables the LTM9001 ADC. Default is
NORM.
ADC Internal Dither. Default is OFF.
1