19-6158; Rev 0; 12/11
EVALUATION KIT AVAILABLE
MAX2691
L2 Band GPS Low-Noise Amplifier
General Description
The MAX2691 low-noise amplifier (LNA) is designed for
GPS L2 applications. Designed in Maxim’s advanced
SiGe process, the device achieves high gain and
low noise figure while maximizing the input-referred 1dB
compression point and the 3rd-order intercept point. The
MAX2691 provides a high gain of 17.5dB and sub 1dB
noise figure.
The device operates from a +1.6V to +3.6V single sup-
ply. The optional shutdown feature in the device reduces
the typical supply current to 4FA. The device is available
in a very small, lead-free, RoHS-compliant, 0.86mm x
0.86mm x 0.65mm wafer-level package (WLP).
S
High-Power Gain: 17.5dB
S
Low-Noise Figure: 0.93dB
S
Integrated 50Ω Output Matching Circuit
S
Low Supply Current: 4.3mA
S
Wide Supply Voltage Range: 1.6V to 3.6V
S
Low Bill of Materials: One Inductor, Two
Capacitors
S
Small Footprint: 0.86mm x 0.86mm
S
Thin Profile: 0.65mm
S
0.4mm-Pitch Wafer-Level Package (WLP)
Ordering Information
appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to
www.maxim-ic.com/MAX2691.related.
Features
Applications
Precision Navigation
Telematics (Asset Tracking and Management)
Avionics
Typical Application Circuit
V
CC
C2
V
CC
MAX2691
A1
A2
RFOUT
RF
OUTPUT
R1
25kI
RF
INPUT
C1
L1
RFIN
B1
B2
GND
SHDN
OPTIONAL SHUTDOWN
MAX2691
L1 = 8.2nH
C1 = 100nF
C2 = 10pF
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Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX2691
L2 Band GPS Low-Noise Amplifier
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND..........................................................-0.3V to +3.6V
Other Pins to GND
(except RFIN) ...................-0.3V to (+ Operating V
CC
+ 0.3V)
Maximum Current into RF Input .........................................10mA
Maximum RF Input Power ............................................... +5dBm
Continuous Power Dissipation (T
A
= +70°C)
4-Bump WLP (derates 9.7mW/°C above +70°C) ........776mW
Operating Temperature Range .......................... -40°C to +85°C
Junction Temperature .....................................................+150°C
Storage Temperature Range............................ -65°C to +160°C
Lead Temperature (soldering, 10s) ........ Reflow Profile (Note 1)
Soldering Temperature (reflow) ......................................+260°C
Note 1:
Refer to Application Note 1891:
Wafer-Level Packaging (WLP) and Its Applications.
CAUTION!
ESD SENSITIVE DEVICE
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(MAX2691 EV kit, V
CC
= 1.6V to 3.6V, T
A
= -40°C to +85°C, no RF signals are applied. Typical values are at V
CC
= 2.85V and
T
A
= +25°C, unless otherwise noted.) (Note 2)
PARAMETER
Supply Voltage
Supply Current
Digital Input Logic-High
Digital Input Logic-Low
SHDN
= high
Shutdown mode,
SHDN
= low
(Note 3)
(Note 3)
1.2
0.45
CONDITIONS
MIN
1.6
TYP
2.85
4.3
4.0
20
MAX
3.6
UNITS
V
mA
µA
V
V
AC ELECTRICAL CHARACTERISTICS
(MAX2691 EV kit, V
CC
= 1.6V to 3.6V, T
A
= -40°C to +85°C, f
RFIN
= 1227MHz. Typical values are at V
CC
= 2.85V and T
A
= +25°C,
unless otherwise noted.) (Note 2)
PARAMETER
RF Frequency
Power Gain (Note 4)
Noise Figure
In-Band 3rd-Order Input
Intercept Point
Input 1dB Compression Point
Input Return Loss
L2 band
V
CC
= 2.85V
V
CC
= 1.6V
V
CC
= 1.6V to 3.3V
(Note 5)
(Note 6)
13.3
13.1
CONDITIONS
MIN
TYP
1227
17.5
17.4
0.93
-3.0
-8.5
10.9
MAX
UNITS
MHz
dB
dB
dBm
dBm
dB
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Maxim Integrated Products
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MAX2691
L2 Band GPS Low-Noise Amplifier
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2691 EV kit, V
CC
= 1.6V to 3.6V, T
A
= -40°C to +85°C, f
RFIN
= 1227MHz. Typical values are at V
CC
= 2.85V and T
A
= +25°C,
unless otherwise noted.) (Note 2)
PARAMETER
Output Return Loss
Reverse Isolation
CONDITIONS
MIN
TYP
15.6
45
MAX
UNITS
dB
dB
Note 2:
Min and max limits guaranteed by test at T
A
= +25°C and guaranteed by design and characterization at T
A
= -40°C and
T
A
= +85°C, unless otherwise noted.
Note 3:
Min and max limits guaranteed by test at T
A
= +25°C.
Note 4:
Min limit guaranteed by design and characterization.
Note 5:
Measured with the two tones located at 1MHz and 2MHz offset from the center of the GPS band with -30dBm/tone.
Note 6:
Measured with a tone located at 5MHz offset from the center of the GPS band.
Typical Operating Characteristics
(MAX2691 EV kit. Typical values are at V
CC
= 2.85V, T
A
= +25°C, and f
RFIN
= 1227MHz, unless otherwise noted.)
INPUT RETURN LOSS vs. FREQUENCY
MAX2691 toc01
GAIN vs. FREQUENCY
MAX2691 toc02
REVERSE ISOLATION vs. FREQUENCY
-10
-20
-30
MAX2691 toc03
0
-5
-10
-15
20
15
10
0
|
S11
|
(dB)
-20
-25
-30
-35
-40
-45
500
1000
1500
FREQUENCY (MHz)
2000
2500
|
S12
|
(dB)
1000
1500
FREQUENCY (MHz)
2000
GAIN (dB)
5
0
-5
-10
500
2500
-40
-50
-60
-70
-80
-90
500
1000
1500
FREQUENCY (MHz)
2000
2500
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Maxim Integrated Products
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MAX2691
L2 Band GPS Low-Noise Amplifier
Typical Operating Characteristics (continued)
(MAX2691 EV kit. Typical values are at V
CC
= 2.85V, T
A
= +25°C, and f
RFIN
= 1227MHz, unless otherwise noted.)
INBAND IIP3 vs. SUPPLY VOLTAGE
AND TEMPERATURE
MAX2691 toc04
OUTPUT RETURN LOSS vs. FREQUENCY
0
-5
-10
-15
-20
-25
500
1000
1500
FREQUENCY (MHz)
2000
2500
2
1
0
IIP3 (dBm)
TWO TONES LOCATED AT +1MHz AND +2MHz
FROM 1227MHz. P
IN
= -30dBm/TONE
T
A
= -40°C
T
A
= +25°C
|
S22
|
(dB)
-1
-2
-3
-4
1.6
2.1
T
A
= +85°C
2.6
3.1
3.6
SUPPLY VOLTAGE (V)
INPUT P1dB COMPRESSION vs.
SUPPLY VOLTAGE AND TEMPERATURE
MAX2691 toc06
1dB GAIN DESENSE vs.
BLOCKER FREQUENCY
MAX2691 toc07
-6
-8
INPUT P1dB (dBm)
-10
T
A
= +85°C
-12
-14
-16
1.6
2.1
2.6
3.1
5
0
BLOCKER POWER (dBm)
T
A
= -40°C
T
A
= +25°C
-5
-10
-15
-20
-25
500
1000
1500
2000
2500
BLOCKER FREQUENCY (MHz)
3.6
SUPPLY VOLTAGE (V)
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Maxim Integrated Products
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MAX2691 toc05
MAX2691
L2 Band GPS Low-Noise Amplifier
Bump Configuration
TOP VIEW
+
V
CC
A1
MAX2691
A2
RFOUT (SHDN)
RFIN
B1
B2
GND
WLP
Bump Description
BUMP
A1
A2
B1
B2
NAME
V
CC
RFOUT
(SHDN)
RFIN
GND
FUNCTION
Supply Voltage. Bypass to ground with a 10pF capacitor as close as possible to the IC.
RF Output/SHDN Input. RFOUT is internally matched to 50I and pulled up to V
CC
through a 1MI
resistor.
SHDN
is shared with the RFOUT bump. The device is in active mode by default once V
CC
is applied. RFOUT(SHDN) can be pulled to a DC low through a 25kI resistor to shut down the IC.
RF Input. Requires a DC-blocking capacitor and external matching components.
Ground. Connect to the PCB ground plane.
Detailed Description
The MAX2691 LNA is designed for GPS L2 applications.
The device features a power-shutdown control mode
to eliminate the need for an external supply switch.
The device achieves high gain, low noise figure, and
excellent linearity.
The MAX2691 requires an off-chip input match. Only an
inductor in series with a DC-blocking capacitor is needed
to form the input matching circuit. The
Typical Application
Circuit
shows the recommended input-matching network.
These values are optimized for the best simultane-
ous gain, noise figure, and return loss performance.
Reducing the input coupling capacitor results in a lower
IIP3. The device integrates an on-chip output matching
to 50I at the output, eliminating the need for external
matching components.
Table 1
lists typical device S
parameters and K
f
values. Typical noise parameters are
shown in
Table 2.
The MAX2691 includes an optional shutdown feature to
turn off the entire chip. The device is placed in active
mode by default once V
CC
is applied, due to the on-chip
pullup resistor to V
CC
at the RFOUT bump (shared with
the
SHDN
input). To shut down the part, apply a logic-low
to the RFOUT bump through an external resistor with an
adequate value, e.g., 25kI, in order not to load the RF
output signal during active operation.
Input and Output Matching
Applications Information
A properly designed PCB is essential to any RF micro-
wave circuit. Use controlled-impedance lines on all
high-frequency inputs and outputs. Bypass V
CC
with
decoupling capacitors located close to the device. For
long V
CC
lines, it may be necessary to add decoupling
capacitors. Locate these additional capacitors further
away from the device package. Proper grounding of
the GND pin is essential. If the PCB uses a topside RF
ground, connect it directly to the GND pin. For a board
where the ground is not on the component layer, connect
the GND pin to the board with multiple vias close to the
package.
Refer to
www.maxim-ic.com
for the MAX2691 EV kit
schematic, Gerber data, PADS layout file, and BOM
information.
Shutdown
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Maxim Integrated Products
5
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