Datasheet

Data Sheet AD8376
Rev. B | Page 13 of 24
APPLICATIONS
BASIC CONNECTIONS
Figure 36 shows the basic connections for operating the
AD8376. 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 AD8376 are open collectors that need to be
pulled up to the positive supply with 1 µH RF chokes. The differ-
ential 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 each channel of the AD8376, the ENBA or ENBB pin
must be pulled high. Taking ENBA or ENBB low puts the
channels of the AD8376 in sleep mode, reducing current
consumption to approximately 5 mA per channel at ambient.
SINGLE-ENDED-TO-DIFFERENTIAL CONVERSION
The AD8376 can be configured as a single-ended input to
differential output driver, as shown in Figure 34. 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.
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 35.
5
0.1µF
0.1µF
0.1µF
0.1µF
37.5Ω
150Ω
1/2
AD8376
1µH
150Ω
A0 TO A4
1µH
+5V
06725-035
VCM
0.1µF
50Ω
AC
Figure 34. Single-Ended-to-Differential Conversion
Featuring ½ of the AD8376
06725-036
–60
–65
–70
–75
–80
–85
–90
–95
–100
HARMONIC DISTORTION (dBc)
0 200150100
50
FREQUENCY (MHz)
HD2
HD3
Figure 35. Harmonic Distortion vs. Frequency of
Single-Ended-to-Differential Conversion