Datasheet
AD813
REV. B
–16–
High Performance Video Line Driver
At a gain of +2, the AD813 makes an excellent driver for a back
terminated 75 Ω video line. Low differential gain and phase
errors and wide 0.1 dB bandwidth can be realized over a wide
range of power supply voltage. Excellent gain and group delay
matching are also attainable over the full operating supply volt-
age range.
75V
75V
AD813
4
11
R
G
R
F
V
IN
V
OUT
75V
+V
S
0.1mF
0.1mF
–V
S
75V
CABLE
75V
CABLE
Figure 46. A Video Line Driver Operating at a Gain of
+2 (R
F
= R
G
from Table I)
G = +2
R
L
= 150V
5V
3V
1
10 1000100
FREQUENCY – MHz
–1
–6
+1
0
–2
–3
–4
–5
CLOSED-LOOP GAIN (NORMALIZED) – dB
+90
0
–90
–180
–270
PHASE SHIFT – Degrees
PHASE
GAIN
V
S
= 615V
65V
V
S
= 615V
65V
3V
5V
Figure 47. Closed-Loop Gain & Phase vs. Frequency for
the Line Driver
216141210864
SUPPLY VOLTAGE – Volts
–3dB BANDWIDTH – MHz
40
30
70
50
60
80
90
20
100
110
120
20180
NO PEAKING
R
F
= 590V
R
F
= 681V
R
F
= 750V
Figure 48. –3 dB Bandwidth vs. Supply Voltage for
Gain = +2, R
L
= 150
Ω
100k
1M 100M10M
FREQUENCY – Hz
0
0.2
0.1
–0.1
–0.2
–0.3
–0.4
NORMALIZED GAIN – dB
–0.5
3V
615V
5V
G = +2
R
L
= 150V
65V
Figure 49. Fine-Scale Gain (Normalized) vs. Frequency
1 10 1000100
FREQUENCY – MHz
0
1.0
0.5
–0.5
–1.0
–1.5
–2.0
GAIN MATCHING – dB
1.5
2.0
–2.5
2.5
V
S
= 615V
V
S
= 3V
G = +2
R
L
= 150V
Figure 50. Closed-Loop Gain Matching vs. Frequency
100k 1M 100M10M
FREQUENCY – Hz
4
2
1.0
0.5
0
–0.5
GROUP DELAY – ns
6
8
–1.0
10
V
S
= 615V
3V
V
S
= 3V
DELAY
DELAY MATCHING
615V
65V
5V
Figure 51. Group Delay and Group Delay Matching vs.
Frequency, G = +2, R
L
= 150
Ω
Figures 50 and 51 show the worst case matching; the match
between amplifiers 2 and 3 is typically much better than this.