AD8375ACPZ-WP(Rev0) View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
AD8375ACPZ-WP Datasheet PDF : 24 Pages
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AD8375
APPLICATIONS
BASIC CONNECTIONS
Figure 35 shows the basic connections for operating the
AD8375. A voltage between 4.5 V and 5.5 V should be applied
to the supply pins. Each supply pin should be decoupled with at
least one low inductance, surface-mount ceramic capacitor of
0.1 μF placed as close as possible to the device.
The outputs of the AD8375 are open collectors that need to be
pulled up to the positive supply with 1 μH RF chokes. The
differential outputs are biased to the positive supply and require
ac coupling capacitors, preferably 0.1 μF. Similarly, the input
pins are at bias voltages of about 2 V above ground and should
be ac-coupled as well. The ac coupling capacitors and the RF
chokes are the principle limitations for operation at low
frequencies.
To enable the AD8375, the PWUP pin must be pulled high.
Taking PWUP low puts the AD8375 in sleep mode, reducing
current consumption to 5 mA at ambient.
SINGLE-ENDED-TO-DIFFERENTIAL CONVERSION
The AD8375 can be configured as a single-ended input to
differential output driver as shown in Figure 33. A 150 Ω
resistor in parallel with the input impedance of input pin
provides an impedance matching of 50 Ω. The voltage gain and
the bandwidth of this configuration, using a 150 Ω load,
remains the same as when using a differential input.
VCM
0.1µF
150Ω
0.1µF
+5V
1µH 1µH
0.1µF
50Ω
0.1µF AD8375
AC
37.5Ω
5
0.1µF
150Ω
A0 TO A4
Figure 33. Single-Ended-to-Differential Conversion
Using a single-ended input decreases the power gain by 3 dB
and limits distortion cancellation. Consequently, the second-
order distortion is degraded. The third-order distortion remains
low to 200 MHz, as shown in Figure 34.
–60
–65
HD2
–70
–75
–80
–85
–90
HD3
–95
–100
0
50
100
150
200
FREQUENCY (MHz)
Figure 34. Harmonic Distortion vs. Frequency of
Single-Ended-to-Differential Conversion
+VS
BALANCED
SOURCE
RS
2
AC
RS
2
0.1µF
0.1µF
24 23 22 21 20 19
COMM VPOS COMM COMM COMM PWUP
1 VCOM
VOUT– 18
2 VIN+
VOUT+ 17
0.1µF
3 VIN–
4 A4
AD8375
VOUT– 16
VOUT+ 15
5 A3
COMM 14
6 A2
A1
7
VPOS 13
A0 VPOS VPOS COMM VPOS
8
9
10 11 12
0.1µF 10µF
1µH
0.1µF
1µH
RL
0.1µF
BALANCED
LOAD
PARALLEL CONTROL INTERFACE
0.1µF
+VS
0.1µF
Figure 35. Basic Connections
Rev. 0 | Page 13 of 24
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