AD8001A Analog Devices, AD8001A Datasheet - Page 12

• Manufacturer Part Number: AD8001A
• Description: 800 Mhz, 50 MW Current Feedback Amplifier
• Manufacturer: Analog Devices

AD8001
Communications
Distortion is a key specification in communications applications.
Intermodulation distortion (IMD) is a measure of the ability of
an amplifier to pass complex signals without the generation of
spurious harmonics. The third order products are usually the
most problematic since several of them fall near the fundamen-
tals and do not lend themselves to filtering. Theory predicts that
the third order harmonic distortion components increase in
power at three times the rate of the fundamental tones. The
specification of third order intercept as the virtual point where
fundamental and harmonic power are equal is one standard
measure of distortion performance. Op amps used in closed-
loop applications do not always obey this simple theory. At a
gain of two, the AD8001 has performance summarized in Fig-
ure 46. Here the worst third order products are plotted vs. input
power. The third order intercept of the AD8001 is +33 dBm at
10 MHz.
Figure 46. Third Order IMD; F
–45
–50
–55
–60
–65
–70
–75
–80
–8
–7
–6
G = +2
F
F
1
2
= 10MHz
= 12MHz
–5
–4
INPUT POWER – dBm
–3
–2
–1
1
0
= 10 MHz, F
2F
1
2
– F
2
1
3
2F
1
– F
4
2
= 12 MHz
2
5
6
–12–
Operation as a Video Line Driver
The AD8001 has been designed to offer outstanding perfor-
mance as a video line driver. The important specifications of
differential gain (0.01%) and differential phase (0.025 ) meet
the most exacting HDTV demands for driving one video load.
The AD8001 also drives up to two back terminated loads as
shown in Figure 47, with equally impressive performance (0.01%,
0.07 ). Another important consideration is isolation between
loads in a multiple load application. The AD8001 has more
than 40 dB of isolation at 5 MHz when driving two 75
terminated loads.
V
IN
CABLE
75
909
75
Figure 47. Video Line Driver
AD8001
+V
–V
909
S
S
0.001 F
0.001 F
+
0.1 F
0.1 F
75
75
CABLE
CABLE
75
75
75
75
V
V
OUT
REV. C
OUT
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