Application Note

VISHAY VITRAMON
Multilayer Chip Capacitors
Application Note
VJ 6040 Tuning Circuit and Channel Selection
VJ 6040 TUNING CIRCUIT AND CHANNEL
SELECTION
VJ 6040 is a narrow band antenna that requires an active
digital tuning circuit to allow it to cover the UHF band which
spans between 470 MHz and 860 MHz.
SCHEMATICS
Figure 1 presents the schematic
recommended tuning circuit.
of
the
VJ 6040
VJ 6040 reference tuning circuit is composed of two PIN
diodes that enable four channels within the UHF band. This
document describes these channels, and offers a detailed
description regarding how to control the tuning circuit to
obtain optimal antenna efficiency.
Applications that do not require the full coverage of the UHF
band can enjoy added efficiency by setting VJ 6040 to a
single fixed channel.
drawing
C6
L1
L3
R1
Digital Input 1
D0
The values described in this application note have been
measured using the VJ 6040 evaluation kit.
D1
C1
L4
R2
D2
L2
VJ 6040 REFERENCE TUNING CIRCUIT
The aggressive antenna miniaturization process that
resulted in the ultra-small form factor of the antenna also
caused the unwanted effect of reducing the antenna
bandwidth to approximately 120 MHz at - 3 dBi from its peak
value. Full coverage of the UHF band (470 MHz to 860 MHz)
can be achieved by implementing a simple four channel
active digital tuning circuit. The tuning circuit shifts the
central operating frequency of the antenna, thus allowing full
coverage of the UHF band.
L5
R3
Digital Input 2
D1
C4
C5
C7
C2
Tuning circuit key features are:
• Small outline - fits onto a single side PCB of 5 mm x 5 mm
50 Ω RF feed
• Low cost BOM)
Fig. 1 - Tuning Circuit Schematics
• Robust design not affected by interference sources such
as GSM
Document Number: 45159
Revision: 06-Jul-09
For technical questions, contact: mlcc@vishay.com
www.vishay.com
1
APPLICATION NOTE
• Digitally controlled - two digital control pins enable
coverage of the entire band, by offering 4 combinations
Application Note
Vishay Vitramon
VJ 6040 Tuning Circuit and Channel Selection
LAYOUT
Figure 2 shows the recommended layout of the tuning circuit. Layout should be as compact as possible.
VISHAY
VJ 6040
L1
C3
L3
R1
C6
Digital Input 1
C1
L4
R2
D1
C7
L2
C6 C4
L5
Digital Input 2
R3
D2
C2
Legend
50 Ω Line
Ground plane copper area on top, botton and/or
inner layers
Conducting strip lines
0402 component
to the Receiver
Via hole to ground plane
Fig. 2 - Tuning Circuit Layout
REFERENCE TUNING CIRCUIT BOM
APPLICATION NOTE
TABLE 1 - TUNING CIRCUIT BILL OF MATERIALS
VALUE
REFERENCE
QUANTITY PER CIRCUIT
PART NUMBER
MANUFACTURER
120 nH
L3, L4, L5
3
HK 1005 R12J
Taiyo Yuden
PIN diode
D1, D2
2
????
Infineon
39 nH
L2
1
IMC0402ER39NJ
Vishay
47 nH
L1
1
IMC0402ER47NJ
Vishay
2.2 pF
C1, C5
2
VJ0402A2R2BXAC-W1BC
Vishay
220 pF
C2, C3, C4, C6, C7
5
VJ0402A221JXAC-W1BC
Vishay
1 kW
R1, R3
2
CRCW1KJNED
Vishay
0W
R2
1
CRCW0R0Z0ED
Vishay
Note
• Any changes made in the reference BOM might result in loss of radiation efficiency.
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2
For technical questions, contact: mlcc@vishay.com
Document Number: 45159
Revision: 06-Jul-09
Application Note
Vishay Vitramon
VJ 6040 Tuning Circuit and Channel Selection
SINGLE CHANNEL
Applications that require less than full coverage of the UHF band can remove the tuning circuit and set the antenna to a single
channel centered at any point within the UHF band. The single channel tuning circuit is comprised of two components as
described below:
VJ 6040
L1
C1
50 Ω RF feed
Fig. 3 - Single Tuning Circuit Layout
For example, setting VJ 6040 to a single channel centered at 725 MHz, can be achieved by assembling a 47 nH inductor at L1,
and a 3.9 pF capacitor at C1. Contact Vishay Vitramon technical support for more details regarding single channel tuning circuit
values.
CONTROL SIGNAL INTEGRITY
The following table describes the desired control signal properties:
TABLE 2 - SIGNAL INTEGRITY FOR ELECTRICAL CONTROL ALTERNATIVE
PARAMETER
SYMBOL
MIN.
TYP.
MAX.
UNITS
COMMENTS
Equivalent DC Circuit
Vih
Logical LOW
- 0.3
0
0.2
V
1 kΩ
Vil
Equivalent DC Circuit
Vih
2
3
5
V
Sink current
Isink
0
0.01
0.05
mA
Vin = - 0.3 V
Diode reverse leakage current
Source current
Isource
4
4.2
5
mA
Vin = 5 V
1 kΩ
Logical HIGH
Note
• Any changes made in the reference BOM might result in loss of radiation efficiency.
Document Number: 45159
Revision: 06-Jul-09
For technical questions, contact: mlcc@vishay.com
www.vishay.com
3
APPLICATION NOTE
Vih
Application Note
Vishay Vitramon
VJ 6040 Tuning Circuit and Channel Selection
CHANNEL CHARACTERISTICS
The two digital control lines offer four frequency channels as described in the table 3 below. This table shows the peak gain
obtained in each of the four channels.
TABLE 3
PARAMETER
D0
D1
BAND (MHz)
S11 (dB)
Return loss
10
1
H
L
470 to 540
S11 (dB)
0
460
510
560
610
660
710
760
810
860
- 10
- 20
- 30
- 40
- 50
f (MHz)
Return loss
0
460
560
660
760
860
760
860
-2
L
L
540 to 580
-4
S11 (dB)
2
-6
-8
- 10
- 12
f (MHz)
Return loss
0
460
560
660
3
H
H
620 to 750
S11 (dB)
-2
-4
-6
-8
- 10
- 12
f (MHz)
Return loss
460
0
510
560
610
660
710
760
810
860
4
L
H
750 to 860
S11 (dB)
-5
- 10
- 15
- 20
- 25
f (MHz)
APPLICATION NOTE
Features are subject to revisions or changes without notification
The company’s products are covered by one or more of the following:
WO2008250262 (A1), US2008303720 (A1), US2008305750 (A1), WO2008154173 (A1). Other patents pending.
ORDERING INFORMATION
VISHAY MATERIAL
PACKAGING QUANTITY
VJ 6040
VJ6040M011SXISRA0
1000 pieces
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4
For technical questions, contact: mlcc@vishay.com
Document Number: 45159
Revision: 06-Jul-09