Datasheet

LT1806/LT1807
22
18067fc
TYPICAL APPLICATIONS
Single Supply Video Line Driver
The LT1806/LT1807 are wideband rail-to-rail op amps with
large output current that allows them to drive video signals
in low supply applications. Figure 4 depicts a single supply
video line driver with AC coupling to minimize the quies-
cent power dissipation. Resistors R1 and R2 are used to
level-shift the input and output to provide the largest signal
swing. The gain of 2 is set up with R3 and R4 to restore
the signal at V
OUT
, which is attenuated by 6dB due to the
matching of the 75Ω line with the back-terminated resistor,
R5. The back termination will eliminate any refl ection of
the signal that comes from the load. The input termination
resistor, R
T
, is optional—it is used only if matching of
the incoming line is necessary. The values of C1, C2 and
C3 are selected to minimize the droop of the luminance
signal. In some less stringent requirements, the value of
capacitors could be reduced. The –3dB bandwidth of the
driver is about 90MHz on 5V supply, and the amount of
peaking will vary upon the value of capacitor C4.
Figure 4. 5V Single Supply Video Line Driver
–
+
LT1806
V
IN
18067 F04
C1
33μF
C2
150μF
R
T
75Ω
R
LOAD
75Ω
V
OUT
R2
5k
R3
1k
R4
1k
C4
3pF
R1
5k
5V
2
3
6
7
4
R5
75Ω
75W
COAX CABLE
C3
1000μF
+
+
+
Figure 5. Video Line Driver Frequency Response
FREQUENCY (MHz)
–2
VOLTAGE GAIN (dB)
4
5
–3
–4
3
0
2
1
–1
0.2 10 100
18067 F05
–5
1
V
S
= 5V, 0V