LT6551
1
DESCRIPTION
Demonstration circuit 866 is a Quad Video Amplifier fea-
turing the LT6551. The Demo Circuit is designed to oper-
ate from a single pow er supply from 4.5V to 12V. The
inputs and outputs are ac-coupled and include 75
Ω
ter-
minations for video cables. The LT6551 has a fixed volt-
age-gain of tw o, thus w ith a terminated output cable, the
net gain is nominally unity.
Design files for this circuit board are available. Call
the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT and
Pow erPath are trademarks of Linear Technology Corporation.
PERFORMANCE SUMMARY
Specification s are at T
A
= 25°C
SYM BOL PAR AM ETER CON DITION S M IN TYP M AX UN ITS
V+
Input Supply Range
4.5 5 12.0 V
Z
IN
Input Impedance ac-coupled 75
Ω
Z
OUT
Output Impedance ac-coupled
75
Ω
A
Gain Output terminated into 75
Ω
Output terminated into hi-Z
0
+6
dB
dB
BW
Bandw idth -3dB, small-signal 60 M Hz
Crosstalk 10M Hz
65 dB
V
IN
Input signal sw ing V+= 5V, no output clipping
V+= 9V, no output clipping
±0.8
±1.5
V
V
I
S
Pow er Supply Current V+= 5V, no signal
40 m
Α
OPERATING PRINCIPLES
DC866 provides four identical channels of w ideband sig-
nal amplification suitable for driving HDTV or high-
resolution RGB video display cables. Each amplifier sec-
tion of the LT6551 provides a fixed gain of 2, and w ith
series “back-termination” at the outputs (included on the
board), results in unity gain transmission of a video sig-
nal to a destination load, w ith frequency response show n
in Figure 2.
Each input is terminated to analog ground to properly
load the input signal cable. AC-coupling is provided for
both inputs and outputs, along w ith biasing circuitry, to
provide single-supply operation. Figure 3 show s the typi-
cal crosstalk betw een adjacent channels.
Figure 4 show s the material list of the components used
by DC866, and Figure 5 show s the electrical interconnec-
tion.
DEMO CIRCUIT
866
QUICK START GUIDE
LT6551
LT6551
2
QUICK START PROCEDURE
Demonstration circuit 866 is easy to set up to evaluate
the performance of the LT6551. R efer to Figure 1 for
proper measurement equipment setup and follow the
procedure below :
1.
Prior to connecting the pow er supply, preset the out-
put voltage to 5V, or to the desired level, if different.
2.
W ith pow er off, connect the pow er supplies to V+ and
GN D using banana to clip-lead cables.
3.
If using a Netw ork Analyzer, perform the THRU trans-
mission cal w ith all cabling, adapters, impedance con-
verters, etc. in place as the reference 0dB path.
4.
Energize the pow er supply.
5.
Connect the N etw ork Analyzer (if used) to the appro-
priate channels to measure frequency response and
crosstalk as desired.
6.
For video-signal evaluation, connect a component-
video signal source to the inputs and a monitor and/or
video analyzer to the outputs.
COM +
Power Supply
+5.00
+5.00+5.00
+5.00
Inputs
Outputs
Figure 1.
Proper M easurem ent Equipm ent Setup
LT6551
3
10dB/DIV
100kHz – 100M H z 100kHz – 100M H z
Figure 2.
Typical Sm all-Signal Frequency Response
Figure 3.
Typical Adjacent-Channel Crosstalk
Figure 4.
DC866 Bill of M aterial
LT6551
4
Figure 5.
DC866 Electrical Schem atic Diagram