max5885egmtd Maxim Integrated Products, Inc., max5885egmtd Datasheet - Page 11

• Manufacturer Part Number: max5885egmtd
• Description: Max5885 3.3v, 16-bit, 200msps High Dynamic Performance Dac With Cmos Inputs
• Manufacturer: Maxim Integrated Products, Inc.

The MAX5885 also features an active-high power-down
mode, which allows the user to cut the DAC’s current
consumption. A single pin (PD) is used to control the
power-down mode (PD = 1) or reactivate the DAC (PD
= 0) after power-down. Enabling the power-down mode
of this 16-bit CMOS DAC allows the overall power con-
sumption to be reduced to less than 1mW. The
MAX5885 requires 10ms to wake up from power-down
and enter a fully operational state.
The differential voltage existing between IOUTP and
IOUTN can also be converted to a single-ended volt-
age using a transformer (Figure 6) or a differential
amplifier configuration. Using a differential transformer-
coupled output, in which the output power is limited to
0dBm, can optimize the dynamic performance.
However, make sure to pay close attention to the trans-
former core saturation characteristics when selecting a
transformer for the MAX5885. Transformer core satura-
tion can introduce strong 2nd-harmonic distortion,
especially at low output frequencies and high signal
amplitudes. It is also recommended to center tap the
transformer to ground. If no transformer is used, each
DAC output should be terminated to ground with a 50Ω
resistor. Additionally, a 100Ω resistor should be placed
between the outputs (Figure 7).
Figure 5. Detailed Timing Relationship
B0 TO B15
CLKP
CLKN
IOUT
Applications Information
N - 5
Differential Coupling Using a
______________________________________________________________________________________
DIGITAL DATA IS LATCHED ON
THE RISING EDGE OF CLKP
t SETUP
Wideband RF Transformer
Power-Down Operation (PD)
Performance DAC with CMOS Inputs
N - 1
3.3V, 16-Bit, 200Msps High Dynamic
t HOLD
N - 4
OUTPUT DATA IS UPDATED ON
THE FALLING EDGE OF CLKP
t PD
N
N - 3
If a single-ended unipolar output is desirable, IOUTP
should be selected as the output, with IOUTN ground-
ed. However, driving the MAX5885 single ended is not
recommended since additional noise is added (from
the ground plane) in such configurations.
The distortion performance of the DAC depends on the
load impedance. The MAX5885 is optimized for a 50Ω
double termination. It can be used with a transformer
output as shown in Figure 7 or just one 50Ω resistor
from each output to ground and one 50Ω resistor
between the outputs. This produces a full-scale output
power of up to 0dBm depending on the output current
setting. Higher termination impedance can be used at
the cost of degraded distortion performance and
increased output noise voltage.
The transmitter sections of BTS applications serving
CDMA and W-CDMA architectures must generate carri-
ers with minimal coupling of carrier energy into the adja-
cent channels. Similar to the GSM/EDGE model (see the
Multitone Testing for GSM/EDGE Applications section), a
transmit mask (Tx mask) exists for this application. The
spread-spectrum modulation function applied to the carri-
er frequency generates a spectral response, which is uni-
form over a given bandwidth (up to 4MHz) for a W-CDMA-
modulated carrier.
Adjacent Channel Leakage Power Ratio
N + 1
(ACLR) Testing for CDMA- and
W-CDMA-Based Base Station
N - 2
Transceiver Systems (BTS)
t CH
t CL
N + 2
N - 1
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