Datasheet
Video Line Driver
The MAX4310–MAX4315 are well-suited to drive coaxial
transmission lines when the cable is terminated at both
ends, as shown in Figure 5. Cable frequency response
can cause variations in the signal’s flatness.
Driving Capacitive Loads
A correctly terminated transmission line is purely resis
-
tive and presents no capacitive load to the amplifier.
Reactive loads decrease phase margin and may pro
-
duce excessive ringing and oscillation (see
Typical
Operating Characteristics).
Another concern when driving capacitive loads origi-
nates from the amplifier’s output impedance, which
appears inductive at high frequencies. This inductance
forms an L-C resonant circuit with the capacitive load,
which causes peaking in the frequency response and
degrades the amplifier’s phase margin.
Although the MAX4310–MAX4315 are optimized for AC
performance and are not designed to drive highly capaci-
tive loads, they are capable of driving up to 20pF without
oscillations. However, some peaking may occur in the fre-
quency domain (Figure 6). To drive larger capacitive
loads or to reduce ringing, add an isolation resistor
between the amplifier’s output and the load (Figure 7).
The value of RISO depends on the circuit’s gain and
the capacitive load (Figure 8). Figure 9 shows the
MAX4310–MAX4315 frequency response with the isola-
tion resistor and a capacitive load. With higher capaci-
tive values, bandwidth is dominated by the RC network
formed by R
ISO
and C
L
; the bandwidth of the amplifier
itself is much higher. Also note that the isolation resistor
forms a divider that decreases the voltage delivered to
the load.
MAX4310–MAX4315
High-Speed, Low-Power, Single-Supply
Multichannel, Video Multiplexer-Amplifiers
______________________________________________________________________________________ 15
MAX4310/MAX4313
SS
S
S
HH
H
H
DD
D
D
NN
N
N
A
2
A
1
A
0
C
HANNEL SELECTED
0
—
—
X
None, High-Z Output
1
—
—
00
1
—
—
11
MAX4311/MAX4314
SS
SS
HH
HH
DD
DD
NN
NN
A
2
A
1
A
0
C
HANNEL SELECTED
0
—
X X None, High-Z Output
1
—
00 0
1
—
01 1
1
—
10 2
1
—
11 3
MAX4312/MAX4315
SS
SS
HH
HH
DD
DD
NN
NN
A2
A1
A0
CHANNEL SELECTED
0 X X X None, High-Z Output
1000 0
1001 1
1010 2
1011 3
1100 4
1101 5
1110 6
1111 7
Figure 10. High-Speed EV Board Layout—Component Side
Table 2. Input Control Logic
Figure 11. High-Speed EV Board Layout—Solder Side