C1
C2
A1
A2
Top View
SUMMARY
V
BR
=25V; I
R
=20nA; C
d
=33pF(Nom)
DESCRIPTION
The FSD270 is a new hyperabrupt SOT23 packaged dual common cathode varactor
diode , offering users both compact circuit design and impressive performance
comprising tightly controlled CV characteristics, a capacitance of typically 33 pf @
2V,excellent phase noise performance and high Q of 200 min.
This superior performance in the VHF and UHF ranges has been optimised to meet
the high filtering requirements of a wide range of Digital Audio Broadcasting (DAB)
module circuits , mobile radios, pagers, voltage controlled crystal oscillators
(VCXO) and temperature controlled crystal oscillators (TCXO).
FEATURES
Common Cathode dual Diode ( monolithic construction )
VHF- UHF operation
Close tolerance CV characteristics
High Tuning Ratio
Low I
R
, enabling excellent Phase Noise
Performance ( I
R
typically < 200pA @ 20V )
High Q
APPLICATIONS
DAB Receiver Modules for use with:
-Low voltage battery portables
-Hi-Fi
-In car radio
-MP3 players
Voltage and Temperature Controlled Crystal Oscillators
Mobile Radio and Pagers.
ORDERING INFORMATION
The FSD270 is capacitance selected into 3 bands. A reel will only contain one band - A,B or C. Shipments of more
than 1 reel may contain reels from different bands.
FSD270
ISSUE 1 - AUGUST 2002
1
SILICON DUAL VARIABLE CAPACITANCE DIODE
DEVICE
REEL SIZE
TAPE WIDTH
QUANTITY PER REEL
FSD270TA
7
(180mm)
8mm embossed
3000 units
1
2
3
PIN CONFIGURATION
SOT23
Additional CV matching capability:
Zetex recognise that some applications ie filtering in digital audio receiver circuits, require these dual varactors
to be very tightly matched. To meet this requirement devices can be supplied tested into capacitance bands at the
2V condition.
Each ( TA ) reel will contain 3000 devices carrying only diodes tested into a single band and each device will have a
partmark identifying the capacitance band which they meet.
As this is a final test measurement customers will not have the option to specify a capacitance at the time of
ordering and will be obliged to accept the band into which the devices are tested.
- Purchase orders can be placed in multiples of 3000 units / reel for device type FSD270TA
- Samples can be obtained from Zetex Plc quoting device type #FSD270TA
FSD270
ISSUE 1 - AUGUST 2002
2
PARAMETER
SYMBOL
VALUE
UNIT
Forward Current (single diode)
I
F
200
mA
Power Dissipation at T
amb
=25C (a)
Linear Derating Factor
P
D
330
3
mW
mW/C
Operating and Storage Temperature Range
T
j
:T
stg
-55 to +150
C
ABSOLUTE MAXIMUM RATINGS.
NOTES
(a) For a device surface mounted on 25mm x 25mm FR4 PCB with high coverage of single sided 1oz copper,
in still air conditions
PARAMETER
SYMBOL
MIN.
TYP.
MAX.
UNIT
CONDITIONS.
Reverse Breakdown
Voltage
V
BR
25
V
I
R
= 10
A
Reverse Leakage Current
I
R
0.2
20
nA
V
R
= 20V
Temperature Coefficient
400
ppm/C
V
R
= 3V, f=1MHz
Diode Capacitance
C
d
29.7
33.0
36.3
pF
V
R
= 2V, f=1MHz
Capacitance Ratio
C
d
/ C
d
5.0
6.5
V
R
= 2V/20V, f=1MHz
Figure of Merit
Q
200
V
R
= 3V, f=50MHz
ELECTRICAL CHARACTERISTICS (at T
amb
= 25C ).
MIN.
MAX.
UNIT
PART NUMBER
BAND A
29.7
32.1
pF
70A
BAND B
31.9
34.1
pF
70B
BAND C
33.9
36.3
pF
70C
APPLICATIONS INFORMATION
FSD270 in Digital Audio Broadcasting (DAB)
Circuits
Digital audio is set to dominate car radio and other
mobile radio applications. Most of the required
functions can be achieved with a single integrated
circuit. One parts of the circuit that are not integrated
are the Voltage Controlled Oscillator (VCO) used in the
Phase-Locked Loop (PLL) channel selection circuit and
the tracking filters. Figure 1 shows the FSD270 dual
variable capacitance diode (also known as varactor or
tuner diode) in a DAB application.
Most textbook circuits show a single variable
capacitance diode in place of the FSD270. In practice
radio frequency oscillations in the tracking filters can
drive the single diode into conduction on peaks
increasing the bias voltage and giving rise to
undesirable harmonics. Common-cathode variable
capacitance diodes are used to overcome this problem.
The FSD270 dual common cathode device in the space
saving SOT23 package has been optimized for this
application. Zetex application note AN9 covers our
range of variable capacitance diodes and their
applications in detail.
FSD270
ISSUE 1 - AUGUST 2002
3
Figure 1.
FSD270
ISSUE 1 - AUGUST 2002
4
CHARACTERISTICS
FSD270
ISSUE 1 - AUGUST 2002
5
Europe
Zetex plc
Fields New Road
Chadderton
Oldham, OL9 8NP
United Kingdom
Telephone (44) 161 622 4422
Fax: (44) 161 622 4420
uk.sales@zetex.com
Zetex GmbH
Streitfeldstrae 19
D-81673 Mnchen
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, NY11788
USA
Telephone: (631) 360 2222
Fax: (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
These offices are supported by agents and distributors in major countries world-wide.
This publication is issued to provide outline information only which (unless agreed by the Company in writing) may not be used, applied or reproduced
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 plc 2002
N
PACKAGE OUTLINE
PAD LAYOUT DETAILS
DIM
Millimetres
Inches
Min
Max
Min
Max
A
2.67
3.05
0.105
0.120
B
1.20
1.40
0.047
0.055
C
1.10
0.043
D
0.37
0.53
0.0145
0.021
F
0.085
0.15
0.0033
0.0059
G
NOM 1.9
NOM 0.075
K
0.01
0.10
0.0004
0.004
L
2.10
2.50
0.0825
0.0985
N
NOM
0.95
NOM
0.037
PACKAGE DIMENSIONS
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