SEMICONDUCTORS
Evaluation board description
The wide bandwidth of the ZXFV302 4:1 channel video
multiplexer necessitates some care in the layout of the
printed circuit. For this reason Zetex has made
available an Evaluation Board.
The Evaluation Board layout serves as a useful
example for many applications, showing a practical
implementation of the advice given below.
The ZXFV302EV can also be used to evaluate the
ZXFV301 4:1 channel multiplexer. The ZXFV301 and
ZXFV302 devices have very similar ac performance,
with the only difference being in the active channel
selection.
Figures 1, 2 and 3 show the schematic and copper
layout of a double-sided printed circuit board suitable
for evaluation of the device in the laboratory.
BNC connector sockets allow connection to test
instrumentsvia50⍀cables.Theoutputcircuitincludes
a resistor matching circuit to present a load of 150⍀to
the amplifier (equivalent to a 75⍀back-terminated
video line) and simultaneously provide 50⍀output
impedance.
The attenuation of this matching circuit is 15.45 dB. As
the multiplexer is internally configured for a voltage
gain of 1, the overall gain from input to output is
-15.45dB.
ZXFV302EV
ISSUE 1 - SEPTEMBER 2004
4:1 CHANNEL VIDEO MULTIPLEXER EVALUATION BOARD
1
Figure 1 Circuit schematic
PCB design
A continuous ground plane is required under the
device and its signal connection paths, to provide the
shortest possible ground return paths for signals and
power supply filtering.
A double-sided or multi-layer PCB construction is
required, with plated-through via holes providing
closelyspacedlow-inductanceconnectionsfromsome
components to the continuous ground plane (some of
these holes are not visible in the figures for the
Evaluation Board – artworks and NC drill output can be
provided if required).
ZXFV302EV
SEMICONDUCTORS
ISSUE 1 - SEPTEMBER 2004
2
Figure 2 Evaluation circuit top copper layout
(overall dimensions 2.5 x 2.25 inches)
Figure 3 Evaluation board bottom copper layout
(viewed through from top)
Power supply filtering
For the power supply filtering, low inductance surface
mount capacitors are normally required. It has been
found that very good RF decoupling is provided on
each supply using a 1000pF NPO size 0805 or smaller
ceramic surface mount capacitor, closest to the device
pin, with an adjacent 0.1F X7R capacitor. Other
configurations are possible and it may be found that a
single0.01FX7Rcapacitoroneach supplygivesgood
results. However this should be supported by larger
decoupling capacitors elsewhere on the printed circuit
board. Values of 1 to 10F are recommended
particularly where the voltage regulators are located
more than a few inches from the device. These larger
capacitors are recommended to be solid tantalum
electrolytic or ceramic types.
ZXFV302EV
SEMICONDUCTORS
ISSUE 1 - SEPTEMBER 2004
3
Europe
Zetex GmbH
Streitfeldstraße 19
D-81673 München
Germany
Telefon: (49) 89 45 49 49 0
Fax: (49) 89 45 49 49 49
europe.sales@zetex.com
Americas
Zetex Inc
700 Veterans Memorial Hwy
Hauppauge, NY 11788
USA
Telephone: (1) 631 360 2222
Fax: (1) 631 360 8222
usa.sales@zetex.com
Asia Pacific
Zetex (Asia) Ltd
3701-04 Metroplaza Tower 1
Hing Fong Road, Kwai Fong
Hong Kong
Telephone: (852) 26100 611
Fax: (852) 24250 494
asia.sales@zetex.com
Corporate Headquaters
Zetex Semiconductors plc
ZetexTechnologyPark,Chadderton
Oldham, OL9 9LL
United Kingdom
Telephone (44) 161 622 4444
Fax: (44) 161 622 4446
hq@zetex.com
These offices are supported by agents and distributors in major countries world-wide.
Thispublicationis issuedtoprovide outlineinformation onlywhich(unless agreedbythe Companyinwriting)maynot beused,applied orreproduced
for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. The Company
reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service.
For the latest product information, log on to www.zetex.com
© Zetex Semiconductors plc 2004
QTY CCT - REF VALUE DESCRIPTION
Resistors, surface mount
1 R1, 51R 0805
2 R2,R3 1k⍀0805
1 R4 120R 0805
1 R5 10R 0805
1 R6 62R 0805
4 R1 to R4 51R 0805
4 R5toR8 22k⍀0805
1R9 120R 0805
1R10 62R 0805
1R11 10R 0805
5 R12 - R16 47k⍀0805
Capacitors, surface mount
2 1nF 50V ceramic 0805 NPO
6 100nF 25V ceramic 0805 XR7
2 10F 16V Tant Elec size C
Integrated circuits
1 U1 Zetex ZXFV302N16
Miscellaneous
5 BNC socket, PCB straight flange,
e.g. Tyco B35N14H999X99
1 3-way PCB screw terminal
block IMO 20.501/3SB
1 SW1 DIL switch, 8 way
10 TP1 to
TP10 PCB test terminal, red,
W.Hughes 100-107
Evaluation board parts list
