General Description
The MAX2645 is a versatile, high-linearity, low-noise
amplifier designed for 3.4GHz to 3.8GHz wireless local
loop (WLL), wireless broadband access, and digital
microwave radio applications. The device features an
externally adjustable bias control, set with a single resis-
tor, that allows the user to meet minimum linearity require-
ments while minimizing current consumption. The
amplifier's high-gain, low-noise performance and
adjustable input third-order intercept (IP3) allow it to be
used as a low-noise amplifier (LNA) in the receive path, a
PA predriver in the transmit path, or as an LO buffer.
The MAX2645 features a logic-level gain control that pro-
vides a 25dB step reduction in gain, which improves IP3
performance for operation during high input signal level
conditions. Supply current is reduced from 9mA in high-
gain mode to 3mA in low-gain mode. The device also
includes a logic-controlled shutdown mode, which
reduces supply current to 0.1µA. The MAX2645 operates
from a +3V to +5.5V supply and is offered in the miniature
10-pin µMAX package (5mm
3mm) with an exposed
paddle. Its performance has been optimized for use with
the MAX2683/MAX2684 3.5GHz SiGe mixers to provide a
complete high-performance, front-end solution for 3.5GHz
applications.
Applications
Wireless Local Loop
Wireless Broadband Access
Digital Microwave Radios
Features
o 3.4GHz to 3.8GHz Frequency Range
o LNA Performance (High/Low-Gain Modes)
Gain: +14.4dB/-9.7dB
NF: 2.3dB/15.5dB
Input IP3: +4dBm/+13dBm
Supply Current: 9.2mA/2.7mA
o Highly Versatile Application
Receive Path 1st and 2nd Stage LNA
Transmit PA Predriver
LO Buffer
o Adjustable IP3 and Supply Current
o 0.1µA Supply Current in Shutdown Mode
o +3.0V to +5.5V Single-Supply Operation
o 10-Pin µMAX-EP Package (5.0mm x 3.0mm)
MAX2645
________________________________________________________________ Maxim Integrated Products
1
19-1759; Rev 1; 8/03
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
Ordering Information
Pin Configuration appears at end of data sheet.
PART
TEMP RANGE
PIN-PACKAGE
MAX2645EUB
-40
°C to +85°C
10 µMAX-EP*
*EP = exposed paddle.
APPLICATION
CIRCUIT
LNA, LOW NF
14.4/-9.7
2.3/15.5
+4/+13
+10/+15.5
+11.8/+16.2
2.6/16
2.6/16
14.9/-10.7
15.2/-9.7
LNA, HIGH IP3
PA PREDRIVER
GAIN
(dB)
NF
(dB)
IIP3
(dBm)
MAX2645
BIAS AND POWER
MANAGEMENT
RFIN
Z1
RF
INPUT
3.5GHz
C1
HIGH
GAIN
LOW
GAIN
GND
GAIN STEP
SHUTDOWN
LOGIC
INPUTS
R
BIAS
RADIAL STUB
V
CC
RF
OUTPUT
T
LINE
Typical Operating Circuit
EVALUATION KIT
AVAILABLE
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
MAX2645
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation 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.
V
CC
to GND ...........................................................-0.3V to +6.0V
GAIN, SHDN, RFOUT to GND .....................0.3V to (V
CC
+ 0.3V)
RFIN Input Power (50
source)........................................16dBm
Minimum R
BIAS
....................................................................10k
Continuous Power Dissipation (T
A
= +70°C)
10-Pin µMAX-EP
(derate 10.3mW/°C above T
A
= +70°C) ....................825mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
DC ELECTRICAL CHARACTERISTICS
(V
CC
= +3.0V to +5.5V, GAIN = SHDN = V
CC
, R
BIAS
= 20k
, no RF signals applied, T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V, T
A
= +25°C, unless otherwise indicated.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage
3.0
5.5
V
GAIN = V
CC
9.2
10.9
R
BIAS
= 20k
,
T
A
= +25°C
GAIN = GND
2.7
3.9
GAIN = V
CC
11.6
R
BIAS
= 20k
,
T
A
= -40°C to +85°C
GAIN = GND
4.0
GAIN = V
CC
12
Operating Supply Current
R
BIAS
= 15k
,
T
A
= +25°C
GAIN = GND
3.6
mA
Shutdown Supply Current
SHDN = GND
0.1
2
µA
Input Logic Voltage High
GAIN, SHDN
2.0
V
Input Logic Voltage Low
GAIN, SHDN
0.6
V
GAIN = SHDN = V
CC
1
Input Logic Bias Current
GAIN = SHDN = GND
-10
µA
CAUTION! ESD SENSITIVE DEVICE
MAX2645
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
_______________________________________________________________________________________
3
AC ELECTRICAL CHARACTERISTICS--LNA (Low-Noise Figure Application Circuit)
(MAX2645 EV kit, V
CC
= GAIN = SHDN = +3.3V,R
BIAS
= 20k
±1%, P
RFIN
= -20dBm, f
RFIN
= 3550MHz, Z
o
= 50
,
T
A
= +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Frequency Range
(Note 2)
3400
3800
MHz
GAIN = V
CC
12.9
14.4
15.4
Gain (Note 3)
GAIN = GND
-11.8
-9.7
-8.0
dB
Gain Variation over Temperature
T
A
= -40
°C to +85°C, GAIN = V
CC
or GND (Note 4)
±0.3
±0.7
dB
Gain Step
±24.1
dB
GAIN = V
CC
(Note 5)
+4
Input Third-Order Intercept
GAIN = GND (Note 6)
+13
dBm
GAIN = V
CC
-5
Input 1dB Compression Point
GAIN = GND
0
dBm
GAIN = V
CC
(Notes 4, 7)
2.3
3.0
Noise Figure
GAIN = GND
15.5
dB
GAIN = V
CC
25
Reverse Isolation
GAIN = GND
19
dB
Gain Step Transition Time
(Note 8)
1
µs
Turn-On/Turn-Off Time
(Note 9)
0.5
µs
AC ELECTRICAL SPECIFICATIONS--LNA (High-Input IP3 Application Circuit)
(MAX2645 EV kit, V
CC
= GAIN = SHDN = +3.3V,R
BIAS
= 20k
±1%, P
RFIN
= -20dBm, f
RFIN
= 3550MHz, Z
o
= 50
,
T
A
= +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Frequency Range
(Note 2)
3400
3800
MHz
GAIN = V
CC
14.9
Gain
GAIN = GND
-10.7
dB
Gain Variation over Temperature
T
A
= -40
°C to +85°C, GAIN = V
CC
or GND
±0.3
dB
Gain Step
25.6
dB
GAIN = V
CC
(Note 6)
+10.0
Input Third-Order Intercept
GAIN = GND (Note 7)
+15.5
dBm
GAIN = V
CC
-4
Input 1dB Compression Point
GAIN = GND
0
dBm
GAIN = V
CC
2.6
Noise Figure
GAIN = GND
16
dB
GAIN = V
CC
25
Reverse Isolation
GAIN = GND
19
dB
7
8
9
10
11
12
13
14
15
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(HIGH-GAIN MODE)
MAX2645-01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
T
A
= +25°C
T
A
= +85°C
T
A
= -40°C
T
A
= +25°C
T
A
= +85°C
R
BIAS
= 20k
T
A
= -40°C
R
BIAS
= 15k
2.0
3.0
2.5
4.0
3.5
4.5
5.0
3.0
4.0
3.5
4.5
5.0
5.5
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(LOW-GAIN MODE)
MAX2645-02
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
T
A
= +85°C
T
A
= +25°C
T
A
= +25°C
T
A
= +85°C
T
A
= -40°C
T
A
= -40°C
R
BIAS
= 15k
R
BIAS
= 20k
20
15
10
5
0
15
20
25
SUPPLY CURRENT vs. R
BIAS
MAX2645-03
R
BIAS
(k
)
SUPPLY CURRENT (mA)
HIGH GAIN
LOW GAIN
V
CC
= 3.3V V
CC
= 5V
V
CC
= 5V
V
CC
= 3.3V
Typical Operating Characteristics
(MAX2645 EV kit, V
CC
= +3.3V, R
BIAS
= 20k
, f
RFIN
= 3550MHz, T
A
= +25°C, unless otherwise noted.)
MAX2645
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
4
_______________________________________________________________________________________
AC ELECTRICAL SPECIFICATIONS--PA Predriver Application Circuit
(MAX2645 EV kit, V
CC
= GAIN = SHDN = +3.3V,R
BIAS
= 20k
±1%, P
RFIN
= -20dBm, f
RFIN
= 3550MHz, Z
o
= 50
,
T
A
= +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Frequency Range
(Note 2)
3400
3800
MHz
GAIN = V
CC
15.2
Gain
GAIN = GND
-9.7
dB
Gain Variation over Temperature
T
A
= -40
°C to +85°C, GAIN = V
CC
or GND
±0.3
dB
Gain Step
24.9
dB
GAIN = V
CC
(Note 6)
+11.8
Input Third-Order Intercept
GAIN = GND (Note 7)
+16.2
dBm
GAIN = V
CC
-1.8
Input 1dB Compression Point
GAIN = GND
0
dBm
GAIN = V
CC
2.6
Noise Figure
GAIN = GND
16
dB
GAIN = V
CC
25
Reverse Isolation
GAIN = GND
19
dB
Note 1: Limits over temperature guaranteed by correlation to worst-case temperature testing.
Note 2: This is the recommended operating frequency range. Operation outside this frequency range is possible but has not been
characterized. The device is characterized and tested at 3550MHz. For optimum performance at a given frequency, the out-
put matching network must be properly designed. See Applications Information section.
Note 3: Specifications are corrected for board losses (0.25dB at input, 0.25dB at output).
Note 4: Guaranteed by design and characterization.
Note 5: Input IP3 measured with two tones, f
1
= 3550MHz and f
2
= 3551MHz, at -20dBm per tone.
Note 6: Input IP3 measured with two tones, f
1
= 3550MHz and f
2
= 3551MHz, at -12dBm per tone.
Note 7: Specifications are corrected for board losses (0.25dB at input).
Note 8: Time from when GAIN changes state to when output power reaches 1dB of its final value.
Note 9: Time from when SHDN changes state to when output power reaches 1dB of its final value.
MAX2645
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
_______________________________________________________________________________________
5
7
10
9
8
11
12
13
14
15
16
17
3.4
3.5
3.6
3.7
3.8
GAIN vs. FREQUENCY
(HIGH-GAIN MODE)
MAX2645-04
FREQUENCY (GHz)
GAIN (dB)
T
A
= +25
°C
T
A
= +85
°C
T
A
= -40
°C
LOW-NOISE FIGURE CIRCUIT
-15
-12
-13
-14
-11
-10
-9
-8
-7
-6
-5
3.4
3.5
3.6
3.7
3.8
GAIN vs. FREQUENCY
(LOW-GAIN MODE)
MAX2645-05
FREQUENCY (GHz)
GAIN (dB)
T
A
= +85
°C
T
A
= -40
°C
T
A
= +25
°C
LOW-NOISE FIGURE CIRCUIT
13.0
13.6
13.4
13.2
13.8
14.0
14.2
14.4
14.6
14.8
15.0
3.0
3.5
4.5
5.0
5.5
GAIN vs. SUPPLY VOLTAGE
(HIGH-GAIN MODE)
MAX2645-06
SUPPLY VOLTAGE (V)
GAIN (dB)
4.0
T
A
= +25
°C
T
A
= +85
°C
T
A
= -40
°C
LOW-NOISE FIGURE CIRCUIT
-11.0
-10.5
-10.0
-9.5
-9.0
-8.5
-8.0
-7.5
-7.0
3.0
3.5
4.0
4.5
5.0
5.5
GAIN vs. SUPPLY VOLTAGE
(LOW-GAIN MODE)
MAX2645-07
SUPPLY VOLTAGE (V)
GAIN (dB)
T
A
= -40
°C
T
A
= +25
°C
T
A
= +85
°C
LOW-NOISE FIGURE CIRCUIT
22.0
22.5
23.0
23.5
24.0
24.5
25.0
25.5
26.0
3.0
3.5
4.0
4.5
5.0
5.5
GAIN STEP
vs. SUPPLY VOLTAGE
MAX2645-08
SUPPLY VOLTAGE (V)
GAIN STEP (dB)
T
A
= +25
°C
T
A
= +85
°C
T
A
= -40
°C
LOW-NOISE FIGURE CIRCUIT
14.0
14.2
14.6
14.4
14.8
15.0
GAIN vs. R
BIAS
(HIGH-GAIN MODE)
MAX2645-09
R
BIAS
(k
)
GAIN (dB)
15.0
20.0
17.5
22.5
25.0
V
CC
= 5V
V
CC
= 3.3V
LOW-NOISE FIGURE CIRCUIT
-12.0
-11.4
-11.6
-11.8
-11.2
-11.0
-10.8
-10.6
-10.4
-10.2
-10.0
15.0
17.5
20.0
22.5
25.0
GAIN vs. R
BIAS
(LOW-GAIN MODE)
MAX2645-10
R
BIAS
(k
)
GAIN (dB)
V
CC
= 3.3V
V
CC
= 5V
LOW-NOISE FIGURE CIRCUIT
0
1
3
2
4
5
NOISE FIGURE vs. FREQUENCY
(HIGH-GAIN MODE)
MAX2645-11
FREQUENCY (GHz)
NOISE FIGURE (dB)
3.4
3.6
3.5
3.7
3.8
LOW-NOISE FIGURE CIRCUIT
10
13
12
11
14
15
16
17
18
19
20
3.4
3.5
3.6
3.7
3.8
NOISE FIGURE vs. FREQUENCY
(LOW-GAIN MODE)
MAX2645-12
FREQUENCY (GHz)
NOISE FIGURE (dB)
LOW-NOISE FIGURE CIRCUIT
Typical Operating Characteristics (continued)
(MAX2645 EV kit, V
CC
= +3.3V, R
BIAS
= 20k
, f
RFIN
= 3550MHz, T
A
= +25°C, unless otherwise noted.)
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