RFM RO2125A

RO2125A
•
•
•
Ideal for 315 MHz Superhet Receivers
Very Low Series Resistance
Quartz Stability
•
•
Surface-Mount, Ceramic Case with 21 mm2 Footprint
Complies with Directive 2002/95/EC (RoHS)
304.3 MHz
SAW
Resonator
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. Applications include automotive keyless-entry receivers operating in the USA under FCC Part 15, in Canada under
DOC RSS-210, and in Italy.
Absolute Maximum Ratings
Rating
Value
Units
+0
dBm
CW RF Power Dissipation
DC Voltage Between Terminals
Case Temperature
±30
VDC
-40 to +85
°C
260
°C
Soldering Temperature (10 seconds / 5 cycles max.)
SM-2 Case
Electrical Characteristics
Frequency (+25 °C)
Characteristic
Nominal Frequency
Sym
fC
Tolerance from 304.300 MHz
∆fC
2, 3, 4, 5
IL
2, 5, 6
Unloaded Q
QU
50 Ω Loaded Q
QL
Turnover Temperature
TO
Insertion Loss
Quality Factor
Temperature Stability
Turnover Frequency
Frequency Aging
Notes
Test Fixture Shunt Induc-
Typical
0.9
Absolute Value during the First Year
|fA|
Motional Resistance
RM
Motional Inductance
LM
Motional Capacitance
CM
Transducer Static Capacitance
CO
5, 6, 7, 9
LTEST
2, 7
kHz
1.5
dB
40
°C
fC
kHz
0.032
ppm/°C2
ppm/yr
10
1, 6
5
±75
25
6, 7, 8
FTC
Units
MHz
1,500
10
fO
Frequency Temperature Coefficient
Maximum
304.375
16,000
5, 6, 7
DC Insulation Resistance between Any Two Terminals
RF Equivalent RLC Model
Minimum
304.225
1.0
MΩ
10
19
84.9591
5, 6, 7, 9
3.21978
3.0
Lid Symbolization
3.3
Ω
µH
fF
3.6
83
pF
nH
121
CAUTION: Electrostatic Sensitive Device. Observe precautions for handling.
Notes:
1.
2.
3.
4.
5.
6.
7.
Frequency aging is the change in fC 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 subsequent years.
The center frequency, fC, is measured at the minimum insertion loss point,
ILMIN, with the resonator in the 50 Ω test system (VSWR ≤ 1.2:1). The shunt
inductance, LTEST, is tuned for parallel resonance with CO at fC. Typically, fOSCILLATOR or fTRANSMITTER is approximately equal to the resonator fC.
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 government approval, which is the responsibility of the equipment manufacturer.
Unless noted otherwise, case temperature TC = +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: fC, IL, 3 dB bandwidth, fC versus TC, and CO.
8.
9.
Turnover temperature, TO, is the temperature of maximum (or turnover) frequency, fO. The nominal frequency at any case temperature, TC, may be calculated from: f = fO [1 - FTC (TO -TC)2]. Typically oscillator TO is approximately
equal to the specified resonator TO.
This equivalent RLC model approximates resonator performance near the resonant frequency and is provided for reference only. The capacitance CO is the
static (nonmotional) capacitance between the two terminals measured at low
frequency (10 MHz) with a capacitance meter. The measurement includes parasitic capacitance with "NC” pads unconnected. Case parasitic capacitance is
approximately 0.05 pF. Transducer parallel capacitance can by calculated as:
CP ≈ CO - 0.05 pF.
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: [email protected]
http://www.rfm.com
RO2125A-062001
Page 1 of 2
304.3 MHz
SAW Resonator
Equivalent LC Model
Electrical Connections
The SAW resonator is bidirectional and may be installed with either orientation. The two terminals
are interchangeable and unnumbered. The callout
NC indicates no internal connection. The NC pads
assist with mechanical positioning and stability.
External grounding of the NC pads is recommended to help reduce parasitic capacitance in the circuit.
Terminal
0.05 pF*
Co = Cp + 0.05 pF
NC
NC
Cp
*Case Parasitics
Terminal
Rm
Lm
Cm
Temperature Characteristics
The curve shown on the right
accounts for resonator contri-
The test circuit inductor, LTEST, is tuned to resonate with the static capacitance, CO, at FC.
bution only and does not include LC component temperature contributions.
ELECTRICAL TEST
Network Analyzer
0
-50
-50
-100
-100
-150
-150
-200
-80 -60 -40 -20
Typical Circuit Board
Land Pattern
To 50 Ω
From 50 Ω
Network Analyzer
fC = f O , T C = T O
0
(f-fo ) / fo (ppm)
Typical Test Circuit
-200
0 +20 +40 +60 +80
∆T = T C - T O ( °C )
The circuit board land pattern shown below is one possible design. The optimum land pattern is dependent on the circuit board assembly process
which varies by manufacturer. The distance between adjacent land edges
should be at a maximum to minimize parasitic capacitance. Trace lengths
from terminal lands to other components should be short and wide to minimize parasitic series inductances.
(4 Places)
Typical Dimension:
0.010 to 0.047 inch
(0.25 to 1.20 mm)
Case Design
The case material is black alumina with contrasting symbolization. All pads
are nominally centered with respect to the base and consist of 40 to
70 microinches electroless gold on 60-350 micorinches electroless nickel.
Typical Application Circuits
Typical Low-Power Transmitter Application
+9VDC
Modulation
Input
200k Ω
47
C1
L1
(Antenna)
C2
ROXXXXA
Bottom View
Millimeters
RF Bypass
470
A
Typical Local Oscillator Application
Output
+VDC
C1
ROXXXXA
Bottom View
Inches
Dimensions
+VDC
L1
C2
RF Bypass
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.
Min
Max
Min
Max
5.74
5.99
0.226
0.236
B
3.73
3.99
0.147
0.157
C
1.91
2.16
0.075
0.085
D
0.94
1.10
0.037
0.043
E
0.83
1.20
0.033
0.047
F
1.16
1.53
0.046
0.060
G
0.94
1.10
0.037
0.043
H
0.43
0.59
0.017
0.023
K
0.43
0.59
0.017
0.023
M
5.08
5.33
0.200
0.210
N
0.38
0.64
0.015
0.025
P
3.05
3.30
0.120
0.130
E-mail: [email protected]
http://www.rfm.com
RO2125A-062001
Page 2 of 2