19-1759; Rev 1; 8/03
KIT
ATION
EVALU
E
BL
AVAILA
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
General Description
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
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.
Ordering Information
PART
MAX2645EUB
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
10 µMAX-EP*
Applications
Wireless Local Loop
Wireless Broadband Access
Digital Microwave Radios
*EP = exposed paddle.
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
RADIAL STUB
V
CC
APPLICATION
CIRCUIT
LNA, LOW NF
LNA, HIGH IP3
PA PREDRIVER
GAIN
(dB)
14.4/-9.7
14.9/-10.7
15.2/-9.7
NF
(dB)
2.3/15.5
2.6/16
2.6/16
IIP3
(dBm)
+4/+13
+10/+15.5
+11.8/+16.2
LOGIC
INPUTS
GAIN STEP
SHUTDOWN
R
BIAS
BIAS AND POWER
MANAGEMENT
T
LINE
MAX2645
RF
INPUT
3.5GHz
Z1
C1
RFIN
HIGH
GAIN
LOW
GAIN
RF
OUTPUT
GND
________________________________________________________________
Maxim Integrated Products
1
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.
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
MAX2645
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND ...........................................................-0.3V to +6.0V
GAIN,
SHDN,
RFOUT to GND .....................0.3V to (V
CC
+ 0.3V)
RFIN Input Power (50Ω source)........................................16dBm
Minimum R
BIAS
....................................................................10kΩ
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
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.
CAUTION!
ESD SENSITIVE DEVICE
DC ELECTRICAL CHARACTERISTICS
(V
CC
= +3.0V to +5.5V, GAIN =
SHDN
= V
CC
, R
BIAS
= 20kΩ, 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
Supply Voltage
R
BIAS
= 20kΩ,
T
A
= +25°C
Operating Supply Current
R
BIAS
= 20kΩ,
T
A
= -40°C to +85°C
R
BIAS
= 15kΩ,
T
A
= +25°C
Shutdown Supply Current
Input Logic Voltage High
Input Logic Voltage Low
Input Logic Bias Current
SHDN
= GND
GAIN,
SHDN
GAIN,
SHDN
GAIN =
SHDN
= V
CC
GAIN =
SHDN
= GND
-10
2.0
0.6
1
GAIN = V
CC
GAIN = GND
GAIN = V
CC
GAIN = GND
GAIN = V
CC
GAIN = GND
12
3.6
0.1
2
µA
V
V
µA
CONDITIONS
MIN
3.0
9.2
2.7
TYP
MAX
5.5
10.9
3.9
11.6
4.0
mA
UNITS
V
2
_______________________________________________________________________________________
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
MAX2645
AC ELECTRICAL CHARACTERISTICS—LNA (Low-Noise Figure Application Circuit)
(MAX2645 EV kit, V
CC
= GAIN =
SHDN
= +3.3V,R
BIAS
= 20kΩ ±1%, P
RFIN
= -20dBm, f
RFIN
= 3550MHz, Z
o
= 50Ω,
T
A
= +25°C, unless otherwise noted.)
PARAMETER
Frequency Range
Gain (Note 3)
Gain Variation over Temperature
Gain Step
Input Third-Order Intercept
Input 1dB Compression Point
Noise Figure
Reverse Isolation
Gain Step Transition Time
Turn-On/Turn-Off Time
GAIN = V
CC
(Note 5)
GAIN = GND (Note 6)
GAIN = V
CC
GAIN = GND
GAIN = V
CC
(Notes 4, 7)
GAIN = GND
GAIN = V
CC
GAIN = GND
(Note 8)
(Note 9)
(Note 2)
GAIN = V
CC
GAIN = GND
T
A
= -40°C to +85°C, GAIN = V
CC
or GND (Note 4)
CONDITIONS
MIN
3400
12.9
-11.8
14.4
-9.7
±0.3
±24.1
+4
+13
-5
0
2.3
15.5
25
19
1
0.5
3.0
TYP
MAX
3800
15.4
-8.0
±0.7
UNITS
MHz
dB
dB
dB
dBm
dBm
dB
dB
µs
µs
AC ELECTRICAL SPECIFICATIONS—LNA (High-Input IP3 Application Circuit)
(MAX2645 EV kit, V
CC
= GAIN =
SHDN
= +3.3V,R
BIAS
= 20kΩ ±1%, P
RFIN
= -20dBm, f
RFIN
= 3550MHz, Z
o
= 50Ω,
T
A
= +25°C, unless otherwise noted.)
PARAMETER
Frequency Range
Gain
Gain Variation over Temperature
Gain Step
Input Third-Order Intercept
Input 1dB Compression Point
Noise Figure
Reverse Isolation
GAIN = V
CC
(Note 6)
GAIN = GND (Note 7)
GAIN = V
CC
GAIN = GND
GAIN = V
CC
GAIN = GND
GAIN = V
CC
GAIN = GND
(Note 2)
GAIN = V
CC
GAIN = GND
T
A
= -40°C to +85°C, GAIN = V
CC
or GND
CONDITIONS
MIN
3400
14.9
-10.7
±0.3
25.6
+10.0
+15.5
-4
0
2.6
16
25
19
TYP
MAX
3800
UNITS
MHz
dB
dB
dB
dBm
dBm
dB
dB
_______________________________________________________________________________________
3
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
MAX2645
AC ELECTRICAL SPECIFICATIONS—PA Predriver Application Circuit
(MAX2645 EV kit, V
CC
= GAIN =
SHDN
= +3.3V,R
BIAS
= 20kΩ ±1%, P
RFIN
= -20dBm, f
RFIN
= 3550MHz, Z
o
= 50Ω,
T
A
= +25°C, unless otherwise noted.)
PARAMETER
Frequency Range
Gain
Gain Variation over Temperature
Gain Step
Input Third-Order Intercept
Input 1dB Compression Point
Noise Figure
Reverse Isolation
GAIN = V
CC
(Note 6)
GAIN = GND (Note 7)
GAIN = V
CC
GAIN = GND
GAIN = V
CC
GAIN = GND
GAIN = V
CC
GAIN = GND
(Note 2)
GAIN = V
CC
GAIN = GND
T
A
= -40°C to +85°C, GAIN = V
CC
or GND
CONDITIONS
MIN
3400
15.2
-9.7
±0.3
24.9
+11.8
+16.2
-1.8
0
2.6
16
25
19
TYP
MAX
3800
UNITS
MHz
dB
dB
dB
dBm
dBm
dB
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.
Typical Operating Characteristics
(MAX2645 EV kit, V
CC
= +3.3V, R
BIAS
= 20kΩ, f
RFIN
= 3550MHz, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(HIGH-GAIN MODE)
MAX2645-01
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(LOW-GAIN MODE)
MAX2645-02
SUPPLY CURRENT vs. R
BIAS
MAX2645-03
15
14
SUPPLY CURRENT (mA)
13
12
11
10
9
8
7
3.0
3.5
4.0
4.5
5.0
T
A
= -40°C
R
BIAS
= 20kΩ
T
A
= +85°C
T
A
= -40°C
T
A
= +25°C
R
BIAS
= 15kΩ
T
A
= +25°C
T
A
= +85°C
5.0
4.5
SUPPLY CURRENT (mA)
R
BIAS
= 15kΩ
4.0
3.5
T
A
= -40°C
3.0
2.5
2.0
T
A
= -40°C
T
A
= +25°C
T
A
= +25°C
T
A
= +85°C
T
A
= +85°C
20
SUPPLY CURRENT (mA)
15
V
CC
= 5V
10
V
CC
= 3.3V V = 5V
CC
5
V
CC
= 3.3V
0
LOW GAIN
HIGH GAIN
R
BIAS
= 20kΩ
4.5
5.0
5.5
15
5.5
3.0
3.5
4.0
20
R
BIAS
(kΩ)
25
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
4
_______________________________________________________________________________________
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
Typical Operating Characteristics (continued)
(MAX2645 EV kit, V
CC
= +3.3V, R
BIAS
= 20kΩ, f
RFIN
= 3550MHz, T
A
= +25°C, unless otherwise noted.)
MAX2645
GAIN vs. FREQUENCY
(HIGH-GAIN MODE)
MAX2645-04
GAIN vs. FREQUENCY
(LOW-GAIN MODE)
MAX2645-05
GAIN vs. SUPPLY VOLTAGE
(HIGH-GAIN MODE)
14.8
14.6
T
A
= -40°C
MAX2645-06
17
16
15
14
GAIN (dB)
T
A
= -40°C
-5
-6
-7
-8
GAIN (dB)
-9
-10
-11
-12
-13
-14
T
A
= +25°C
T
A
= +85°C
T
A
= -40°C
15.0
14.4
GAIN (dB)
14.2
14.0
13.8
13.6
13.4
13.2
T
A
= +25°C
T
A
= +85°C
13
12
11
10
9
8
7
T
A
= +25°C
T
A
= +85°C
LOW-NOISE FIGURE CIRCUIT
3.4
3.5
3.6
FREQUENCY (GHz)
3.7
3.8
-15
LOW-NOISE FIGURE CIRCUIT
3.4
3.5
3.6
FREQUENCY (GHz)
3.7
3.8
13.0
LOW-NOISE FIGURE CIRCUIT
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
GAIN vs. SUPPLY VOLTAGE
(LOW-GAIN MODE)
MAX2645-07
GAIN STEP
vs. SUPPLY VOLTAGE
MAX2645-08
GAIN vs. R
BIAS
(HIGH-GAIN MODE)
MAX2645-09
-7.0
-7.5
-8.0
-8.5
GAIN (dB)
-9.0
-9.5
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
26.0
25.5
25.0
GAIN STEP (dB)
T
A
= +25°C
15.0
14.8
V
CC
= 5V
24.0
23.5
23.0
22.5
T
A
= +85°C
T
A
= -40°C
LOW-NOISE FIGURE CIRCUIT
3.0
3.5
4.0
4.5
5.0
5.5
GAIN (dB)
24.5
14.6
14.4
V
CC
= 3.3V
14.2
LOW-NOISE FIGURE CIRCUIT
15.0
17.5
20.0
R
BIAS
(kΩ)
22.5
25.0
-10.0
-10.5
-11.0
LOW-NOISE FIGURE CIRCUIT
3.0
3.5
4.0
4.5
22.0
5.0
5.5
14.0
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
GAIN vs. R
BIAS
(LOW-GAIN MODE)
MAX2645-10
NOISE FIGURE vs. FREQUENCY
(HIGH-GAIN MODE)
MAX2645-11
NOISE FIGURE vs. FREQUENCY
(LOW-GAIN MODE)
19
18
NOISE FIGURE (dB)
17
16
15
14
13
12
11
MAX2645-12
-10.0
-10.2
-10.4
-10.6
GAIN (dB)
-10.8
-11.0
-11.2
-11.4
-11.6
-11.8
-12.0
LOW-NOISE FIGURE CIRCUIT
15.0
17.5
20.0
R
BIAS
(kΩ)
22.5
V
CC
= 3.3V
V
CC
= 5V
5
20
4
NOISE FIGURE (dB)
3
2
1
LOW-NOISE FIGURE CIRCUIT
3.4
3.5
3.6
FREQUENCY (GHz)
3.7
3.8
0
25.0
10
LOW-NOISE FIGURE CIRCUIT
3.4
3.5
3.6
FREQUENCY (GHz)
3.7
3.8
_______________________________________________________________________________________
5
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