RO2125A
•
•
•
•
•
Ideal for 315 MHz Superhet Receivers
Very Low Series Resistance
Quartz Stability
Surface-Mount, Ceramic Case with 21 mm
2
Footprint
Complies with Directive 2002/95/EC (RoHS)
The RO2125A is a true one-port, surface-acoustic-wave (SAW) resonator in a surface-mount ceramic case.
It provides reliable, fundamental-mode, quartz frequency stabilization of local oscillators operating at
approximately 304.3 MHz. This SAW is designed for 315 MHz superhet receivers with 10.7 MHz IF. Applica-
tions include automotive keyless-entry receivers operating in the USA under FCC Part 15, in Canada under
DOC RSS-210, and in Italy.
304.3 MHz
SAW
Resonator
Absolute Maximum Ratings
Rating
CW RF Power Dissipation
DC Voltage Between Terminals
Case Temperature
Soldering Temperature (10 seconds / 5 cycles max.)
Value
+0
±30
-40 to +85
260
Units
dBm
VDC
°C
°C
SM-2 Case
Electrical Characteristics
Characteristic
Nominal Frequency
Tolerance from 304.300 MHz
Insertion Loss
Quality Factor
Temperature Stability
Unloaded Q
50
Ω
Loaded Q
Turnover Temperature
Turnover Frequency
Frequency Temperature Coefficient
Frequency Aging
RF Equivalent RLC Model
Absolute Value during the First Year
Motional Resistance
Motional Inductance
Motional Capacitance
Transducer Static Capacitance
Test Fixture Shunt Induc-
Lid Symbolization
DC Insulation Resistance between Any Two Terminals
R
M
L
M
C
M
C
O
L
TEST
5, 6, 7, 9
2, 7
121
3.0
5, 6, 7, 9
Sym
f
C
∆f
C
IL
Q
U
Q
L
T
O
f
O
FTC
|fA|
1, 6
5
1.0
10
84.9591
3.21978
3.3
83
3.6
19
6, 7, 8
Notes
2, 3, 4, 5
2, 5, 6
5, 6, 7
10
Minimum
304.225
Typical
Maximum
304.375
±75
0.9
16,000
1,500
25
f
C
0.032
10
40
°C
kHz
ppm/°C
2
ppm/yr
MΩ
Ω
µH
fF
pF
nH
1.5
Units
MHz
kHz
dB
Frequency (+25 °C)
CAUTION: Electrostatic Sensitive Device. Observe precautions for handling.
Notes:
1.
Frequency aging is the change in f
C
with time and is specified at +65°C or less.
Aging may exceed the specification for prolonged temperatures above +65°C.
Typically, aging is greatest the first year after manufacture, decreasing in subse-
quent years.
The center frequency, f
C
, is measured at the minimum insertion loss point,
IL
MIN
, with the resonator in the 50
Ω
test system (VSWR
≤
1.2:1). The shunt
inductance, L
TEST
, is tuned for parallel resonance with C
O
at f
C
. Typically, f
OS-
CILLATOR
or f
TRANSMITTER
is approximately equal to the resonator f
C
.
One or more of the following United States patents apply: 4,454,488 and
4,616,197.
Typically, equipment utilizing this device requires emissions testing and govern-
ment approval, which is the responsibility of the equipment manufacturer.
Unless noted otherwise, case temperature T
C
= +25°C±2°C.
The design, manufacturing process, and specifications of this device are subject
to change without notice.
Derived mathematically from one or more of the following directly measured
parameters: f
C
, IL, 3 dB bandwidth, f
C
versus T
C
, and C
O
.
8.
Turnover temperature, T
O
, is the temperature of maximum (or turnover) fre-
quency, f
O
. The nominal frequency at any case temperature, T
C
, may be calcu-
lated from: f = f
O
[1 - FTC (T
O
-T
C
)
2
]. Typically
oscillator
T
O
is approximately
equal to the specified
resonator
T
O
.
This equivalent RLC model approximates resonator performance near the reso-
nant frequency and is provided for reference only. The capacitance C
O
is the
static (nonmotional) capacitance between the two terminals measured at low
frequency (10 MHz) with a capacitance meter. The measurement includes para-
sitic capacitance with "NC” pads unconnected. Case parasitic capacitance is
approximately 0.05 pF. Transducer parallel capacitance can by calculated as:
C
P
≈
C
O
- 0.05 pF.
2.
9.
3.
4.
5.
6.
7.
RF Monolithics, Inc.
Phone: (972) 233-2903
Fax: (972) 387-8148
RFM Europe
Phone: 44 1963 251383
Fax: 44 1963 251510
©1999 by RF Monolithics, Inc. The stylized RFM logo are registered trademarks of RF Monolithics, Inc.
E-mail: info@rfm.com
http://www.rfm.com
RO2125A-062001
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RFM [ RF MONOLITHICS, INC ]
