ADL5374ACPZ-R7 Analog Devices Inc, ADL5374ACPZ-R7 Datasheet - Page 14

• Manufacturer Part Number: ADL5374ACPZ-R7
• Description: IC MOD QUAD 3000-4000MHZ 24LFCSP
• Manufacturer: Analog Devices Inc

Specifications of ADL5374ACPZ-R7

• Design Resources: Interfacing ADL5374 to AD9779A Dual-Channel, 1 GSPS High Speed DAC (CN0020)
• Function: Modulator
• Lo Frequency: 2.8GHz ~ 4GHz
• Rf Frequency: 2.8GHz ~ 4GHz
• P1db: 12dBm
• Noise Floor: -159.7dBm/Hz
• Output Power: 5dBm
• Current - Supply: 175mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Test Frequency: 3.8GHz
• Package / Case: 24-VFQFN, 24-CSP Exposed Pad
• Frequency Range: 3000MHz To 4000MHz
• Rf Type: Quadrature
• Supply Voltage Range: 4.75V To 5.25V
• Rf Ic Case Style: LFCSP
• No. Of Pins: 24
• Operating Temperature Range: -40°C To +85°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADL5374ACPZ-R7TR

ADL5374
APPLICATIONS INFORMATION
DAC MODULATOR INTERFACING
The ADL5374 is designed to interface with minimal components
to members of the Analog Devices family of DACs. These DACs
feature an output current swing from 0 to 20 mA, and the
interface described in this section can be used with any DAC
that has a similar output.
Driving the ADL5374 with a TxDAC®
An example of an interface using the
in Figure 29. The baseband inputs of the ADL5374 require a dc
bias of 500 mV. The average output current on each of the outputs
of the AD9779 is 10 mA. Therefore, a single 50 Ω resistor to
ground from each of the DAC outputs results in an average current
of 10 mA flowing through each of the resistors, thus producing
the desired 500 mV dc bias for the inputs to the ADL5374.
The AD9779 output currents have a swing that ranges from 0 to
20 mA. With the 50 Ω resistors in place, the ac voltage swing
going into the ADL5374 baseband inputs ranges from 0 V to 1 V.
A full-scale sine wave out of the
1 V p-p single-ended (or 2 V p-p differential) sine wave with a
500 mV dc bias.
LIMITING THE AC SWING
There are situations in which it is desirable to reduce the ac
voltage swing for a given DAC output current. This can be
achieved through the addition of another resistor to the interface.
This resistor is placed in the shunt between each side of the
differential pair, as shown in Figure 30. It has the effect of
reducing the ac swing without changing the dc bias already
established by the 50 Ω resistors.
Figure 29. Interface Between the AD9779 and ADL5374 with 50 Ω Resistors to
Ground to Establish the 500 mV dc Bias for the ADL5374 Baseband Inputs
AD9779
OUT1_N
OUT2_N
OUT1_P
OUT2_P
92
93
84
83
RBQN
RBQP
RBIP
RBIN
50Ω
50Ω
50Ω
50Ω
AD9779
AD9779
can be described as a
TxDAC is shown
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The value of this ac voltage swing limiting resistor is chosen
based on the desired ac voltage swing. Figure 31 shows the
relationship between the swing-limiting resistor and the peak-
to-peak ac swing that it produces when 50 Ω bias-setting
resistors are used.
FILTERING
It is necessary to place an anti-aliasing filter between the DAC
and modulator to filter out Nyquist images and broadband
DAC noise. The interface for setting up the biasing and ac
swing discussed in the Limiting the AC Swing section lends
itself well to the introduction of such a filter. The filter can be
inserted between the dc bias setting resistors and the ac swing-
limiting resistor. Doing so establishes the input and output
impedances for the filter.
AD9779
Figure 31. Relationship Between the AC Swing-Limiting Resistor and the
OUT1_N
OUT2_N
OUT1_P
OUT2_P
Figure 30. AC Voltage Swing Reduction Through the Introduction
Peak-to-Peak Voltage Swing with 50 Ω Bias-Setting Resistors
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
10
93
92
84
83
of a Shunt Resistor Between Differential Pair
RBQN
RBQP
RBIN
RBIP
50Ω
50Ω
50Ω
50Ω
100
R
L
RSLQ
(Ω)
100Ω
100Ω
RSLI
1000
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