LT6411
13
6411f
TYPICAL APPLICATIONS
Figure 9. 2-Tone Response of the LT6411 Confi gured with
Single-Ended Inputs Driving the LTC2249 at 29.5MHz, 30.5MHz
Twisted-Pair Line Driver
The LT6411 is ideal when used for driving inexpensive
unshielded twisted-pair wires as often found in telephone
or communications infrastructure. The input can be com-
posite video, or if three parts are used, RGB or similar and
can be either single ended or differential. The LT6411 has
excellent performance with all formats.
Double termination of the video cable will enhance fi delity
and isolate the LT6411 from capacitive loads. Although
most twisted-pair cables have a characteristic impedance
Figure 10. Twisted-Pair Driver
FREQUENCY (MHz)
0
–140
AMPLITUDE (dBFS)
–120
–100
–80
0
–40
5
15
20 40
6411 F09
–20
–60
–130
–110
–90
–10
–50
–30
–70
10
25
30 35
32768 POINT FFT
TONE 1 AT 29.5MHz, –7dBFS
TONE 2 AT 30.5MHz, –7dBFS
IM3 = –90dBc
13
50Ω
100Ω
50Ω
5V
–5V
6,9,10
1,2,3,7
6411 F10
RECEIVER
5
LT6411
A
V
= 2
IN
+
IN
–
+
–
14
15
16
11,12
of 100Ω, the cables can be terminated with a smaller
series resistance or a larger shunt resistance in order to
compensate for attenuation. A typical circuit for a twisted-
pair driver is shown in Figure 10.
Single Supply Differential ADC Driver
The LT6411 is well suited for driving differential analog
to digital converters. The low output impedance of the
LT6411 is capable of driving a variety of fi lters as well as
interfacing with the typically high impedance inputs of
ADCs. In addition, the LT6411’s excellent distortion allows
the part to perform with an SFDR below the limits of many
high speed ADCs. The DC1057 demo board, shown sche-
matically in Figure 11 and physically in Figure 12, allows
implementation and testing of the LT6411 with a variety
of different Linear Technology high speed ADCs.
