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©2008 by RF Monolithics, Inc. RO3118 - 3/27/08
Electrical Characteristics
Characteristic Sym Notes Minimum Typical Maximum Units
Frequency (+25 °C) Nominal Frequency fC2, 3, 4, 5 317.925 318.075 MHz
Tolerance from 318.000 MHz ΔfC±75 kHz
Insertion Loss IL 2, 5, 6 1.5 2.0 dB
Quality Factor Unloaded Q QU5, 6, 7 10700
50 Ω Loaded Q QL1400
Temperature Stability Turnover Temperature TO6, 7, 8 10 25 40 °C
Turnover Frequency fOfC+4.2 kHz
Frequency Temperature Coefficient FTC 0.037 ppm/°C2
Frequency Aging Absolute Value during the First Year |fA| 1, 6 10 ppm/yr
DC Insulation Resistance between Any Two Pins 5 1.0 MΩ
RF Equivalent RLC Model Motional Resistance RM5, 6, 7, 9 15 Ω
Motional Inductance LM80 µH
Motional Capacitance CM3.1 fF
Pin 1 to Pin 2 Static Capacitance CO5, 6, 9 2.6 pF
Trans ducer Static Capacitance CP5, 6, 7, 9 3.0 pF
Test Fixture Shunt Inductance LTEST 2, 7 96 nH
Lid Symbolization (in addition to Lot and/or Date Codes) RFM // RO3118
TO39-3 Case
• Designed for 318 MHz Transmitter Applications
• Low Series Resistance
• Quartz Stability
• Rugged, Hermetic, Low-Profile TO39 Case
• Complies with Directive 2002/95/EC (RoHS)
The RO31 18 is a true one-port, surface-acoustic-wave (SAW) resonator in a low-profile TO39 case. It provides
reliable, fundamental-mode quartz frequency stabi lization of fixed-frequency transmitters operating at or near
318 MHz.
Absolute Maximum Ratings
Rating Value Units
CW RF Power Dissipation +0 dBm
DC Voltage Between Terminals (Observe ESD Precautions) ±30 VDC
Case Temperature -40 to +85 °C
Soldering Temperature (10 seconds / 5 cycles max. 260 °C
318.00 MHz
SAW
Resonator
RO3118
CAUTION: Electrostatic Sensitive Device. Observe precautions for handling.
Notes:
1. Frequency aging is the change in fC with time and is specified at +65°C or
less. Aging may exceed the specific ation for prolonged temperatures
above +65°C. Typically, aging is greatest the first year after manufacture,
decreasing significantly in subsequent years.
2. The center frequency, f C, is measured at the minimum insertion loss point,
ILMIN, with the res onator in the 50 Ω test system (VSWR ≤ 1.2:1). The
shunt inductance, LTEST, is tuned for parallel resonance with CO at fC.
Typ ica lly, fOSCILLATOR or fTRANSMITTER is less than the resonator fC.
3. One or more of the following United States pat ents apply: 4,454,488 and
4,616,197 and others pending.
4. Typically, equipment designs utilizing this device require emissions testing
and government approval, which is the responsibility of the equipmen t
manufacturer.
5. Unless noted otherwise, case temperature TC= +25°C±2°C.
6. The design, manufacturing process, and specifications of this device are
subject to change without notice .
7. Derived mat hematically from one or more of the following directly
measured parameters: fC, IL, 3 dB bandwidth, fC versus TC, and CO.
8. Turnover temperature, TO, is the temperature of maximum (or turnov er)
frequenc y, fO. The nomina l frequenc y at an y case te mperature, TC, may be
calculated from: f = fO[1 - FTC (TO-TC)2]. Typical ly, oscillator TO is 20°C
less than the specified resonator T O.
9. This equiv alent RLC model approximates reso nator performance near the
resonan t frequen cy and is provided for refer ence o nly. The ca pacit ance C O
is the static (nonmotional) capacitance between pin1 and pin 2 measured
at low frequency (10 MHz) with a capacitance meter. The measurement
includes case parasi tic capacitance with a floa ting case. For usual
ground ed case applications (with ground connected to either pin 1 or pin 2
and to the case), add approximately 0.25 pF to CO.
Pb
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©2008 by RF Monolithics, Inc. RO3118 - 3/27/08
Electrical Connections
This one-port, two-terminal SAW resonator is bidirectional. The terminals
are interchangeable with the exception of circuit board layout.
Typical Test Circuit
The test circuit inductor, LTEST, is tuned to resonate with the static
capacitance, CO at FC.
Typical Application Circuits
Temperature Characteristics
Equivalent LC Model
The following equivalent LC model is valid near resonance:
Case Design
Pin Connection
1 Terminal 1
2 Terminal 2
3 Case Ground
Network
Analyzer Network
Analyzer
Electri cal Test:
12
3
ΩΩ
50
Ω
Source at
F
C
Low-Loss
Matching
Network
50
Ω
to
Pow er Test:
P
P
INCIDENT
INCIDENT
CW RF Po wer Di s s i pation = -
REFLECTED
REFLECTED
P
P
3
2
1
MPS-H10
+9VDC
47
RF Bypass
L1
C1
C2
200k
Ω
Modulation
Input
ROXXXX
Botto m V iew
470
Typ i cal Low-Power T r ansmitter A pp li ca ti on :
1
2
3
(Antenna)
+VDC
RF Bypass
L1
C2
ROXXXX
Bottom View
Typical Local Oscillator Application:
12
3
Output
+VDC
C1
Dimensions Millimeters Inches
Min Max Min Max
A9.300.366
B3.180.125
C 2.50 3.50 0.098 0.138
D 0.46 Nominal 0. 018 Nominal
E 5.08 Nominal 0.200 Nominal
F 2.54 Nominal 0.100 Nominal
G 2.54 Nominal 0.100 Nominal
H1.020.040
J 1.40 0.055
The curve shown on the right
accounts for resonator
contribution only and does not
include oscillator temperature
characteristics.
-80 -60 -40 -20 0 +20 +40 +60
0
-50
-100
-150
+80
-200
0
-50
-100
-150
-200
f
C
= f
O
, T
C
= T
O
Δ
T = T
C
- T
O
( °C )
(f-foo
)/f(ppm)
0.5 p F*
0.25 pF*
Cp
Co=+
*Case Parasitics
R
L
C
0.5 pF*
Cp
1
2
3
MMM
B
45°
J
(2 places)
D
(3 places)
H
G
EF
C
A
Bot to m View
Pin 1 Pin 2
Pin 3
