19-1759; Rev 1; 8/03
KIT
ATION
EVALU
E
L
B
A
IL
AVA
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
Applications
Features
♦ 3.4GHz to 3.8GHz Frequency Range
♦ 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
♦ Highly Versatile Application
Receive Path 1st and 2nd Stage LNA
Transmit PA Predriver
LO Buffer
♦ Adjustable IP3 and Supply Current
♦ 0.1µA Supply Current in Shutdown Mode
♦ +3.0V to +5.5V Single-Supply Operation
♦ 10-Pin µMAX-EP Package (5.0mm x 3.0mm)
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX2645EUB
-40°C to +85°C
10 µMAX-EP*
*EP = exposed paddle.
Wireless Local Loop
Pin Configuration appears at end of data sheet.
Wireless Broadband Access
Digital Microwave Radios
Typical Operating Circuit
RADIAL STUB
APPLICATION
CIRCUIT
LNA, LOW NF
LNA, HIGH IP3
PA PREDRIVER
VCC
LOGIC
INPUTS
GAIN STEP
SHUTDOWN
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
BIAS AND POWER
MANAGEMENT
TLINE
RBIAS
MAX2645
C1
RF
INPUT
3.5GHz
RF
OUTPUT
HIGH
GAIN
RFIN
Z1
LOW
GAIN
GND
________________________________________________________________ Maxim Integrated Products
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.
1
MAX2645
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 resistor, that allows the user to meet minimum linearity requirements 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 provides 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 highgain 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.
MAX2645
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
ABSOLUTE MAXIMUM RATINGS
VCC to GND ...........................................................-0.3V to +6.0V
GAIN, SHDN, RFOUT to GND .....................0.3V to (VCC + 0.3V)
RFIN Input Power (50Ω source)........................................16dBm
Minimum RBIAS ....................................................................10kΩ
Continuous Power Dissipation (TA = +70°C)
10-Pin µMAX-EP
(derate 10.3mW/°C above TA = +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
(VCC = +3.0V to +5.5V, GAIN = SHDN = VCC, RBIAS = 20kΩ, no RF signals applied, TA = -40°C to +85°C. Typical values are at VCC
= +3.3V, TA = +25°C, unless otherwise indicated.) (Note 1)
PARAMETER
CONDITIONS
Supply Voltage
Operating Supply Current
2
TYP
MAX
UNITS
5.5
V
10.9
3.0
RBIAS = 20kΩ,
TA = +25°C
GAIN = VCC
9.2
GAIN = GND
2.7
RBIAS = 20kΩ,
TA = -40°C to +85°C
GAIN = VCC
11.6
GAIN = GND
4.0
RBIAS = 15kΩ,
TA = +25°C
GAIN = VCC
12
GAIN = GND
3.6
Shutdown Supply Current
SHDN = GND
Input Logic Voltage High
GAIN, SHDN
Input Logic Voltage Low
GAIN, SHDN
Input Logic Bias Current
MIN
0.1
µA
0.6
V
V
1
-10
_______________________________________________________________________________________
mA
2
2.0
GAIN = SHDN = VCC
GAIN = SHDN = GND
3.9
µA
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
(MAX2645 EV kit, V CC = GAIN = SHDN = +3.3V,R BIAS = 20kΩ ±1%, P RFIN = -20dBm, f RFIN = 3550MHz, Z o = 50Ω,
TA = +25°C, unless otherwise noted.)
PARAMETER
Frequency Range
Gain (Note 3)
Gain Variation over Temperature
CONDITIONS
MIN
TYP
MAX
UNITS
3800
MHz
(Note 2)
3400
GAIN = VCC
12.9
14.4
15.4
GAIN = GND
-11.8
-9.7
-8.0
±0.3
±0.7
TA = -40°C to +85°C, GAIN = VCC or GND (Note 4)
±24.1
Gain Step
Input Third-Order Intercept
Input 1dB Compression Point
GAIN = VCC (Note 5)
+4
GAIN = GND (Note 6)
+13
GAIN = VCC
-5
GAIN = GND
0
dB
dB
dB
dBm
dBm
GAIN = VCC (Notes 4, 7)
2.3
GAIN = GND
15.5
GAIN = VCC
25
GAIN = GND
19
Gain Step Transition Time
(Note 8)
1
µs
Turn-On/Turn-Off Time
(Note 9)
0.5
µs
Noise Figure
Reverse Isolation
3.0
dB
dB
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,
TA = +25°C, unless otherwise noted.)
PARAMETER
Frequency Range
CONDITIONS
(Note 2)
Gain
Gain Variation over Temperature
Input 1dB Compression Point
Noise Figure
Reverse Isolation
TYP
MAX
UNITS
3800
MHz
GAIN = VCC
14.9
GAIN = GND
-10.7
TA = -40°C to +85°C, GAIN = VCC or GND
±0.3
dB
25.6
+10.0
+15.5
-4
0
2.6
16
25
19
dB
GAIN = VCC (Note 6)
GAIN = GND (Note 7)
GAIN = VCC
GAIN = GND
GAIN = VCC
GAIN = GND
GAIN = VCC
GAIN = GND
Gain Step
Input Third-Order Intercept
MIN
3400
dB
dBm
dBm
dB
dB
_______________________________________________________________________________________
3
MAX2645
AC ELECTRICAL CHARACTERISTICS—LNA (Low-Noise Figure Application Circuit)
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,
TA = +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
Frequency Range
MIN
(Note 2)
Gain
Gain Variation over Temperature
Input Third-Order Intercept
Input 1dB Compression Point
Noise Figure
Reverse Isolation
TYP
3400
MAX
UNITS
3800
MHz
GAIN = VCC
15.2
GAIN = GND
-9.7
TA = -40°C to +85°C, GAIN = VCC or GND
±0.3
dB
24.9
dB
Gain Step
GAIN = VCC (Note 6)
+11.8
GAIN = GND (Note 7)
GAIN = VCC
GAIN = GND
GAIN = VCC
GAIN = GND
GAIN = VCC
GAIN = GND
+16.2
-1.8
0
2.6
16
25
19
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 output 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, f1 = 3550MHz and f2 = 3551MHz, at -20dBm per tone.
Note 6: Input IP3 measured with two tones, f1 = 3550MHz and f2 = 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, VCC = +3.3V, RBIAS = 20kΩ, fRFIN = 3550MHz, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(HIGH-GAIN MODE)
12
TA = +85°C
11
TA = -40°C
TA = +25°C
10
9
TA = -40°C
8
RBIAS = 15kΩ
4.0
TA = +85°C
TA = +25°C
3.5
TA = +85°C
TA = -40°C
TA = +25°C
3.0
2.5
RBIAS = 20kΩ
7
TA = -40°C
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
MAX2645-03
15
VCC = 5V
10
HIGH GAIN
VCC = 3.3V V = 5V
CC
5
LOW GAIN
RBIAS = 20kΩ
VCC = 3.3V
2.0
3.0
4
4.5
SUPPLY CURRENT (mA)
TA = +25°C
SUPPLY CURRENT vs. RBIAS
20
SUPPLY CURRENT (mA)
TA = +85°C
RBIAS = 15kΩ
13
5.0
MAX2645-02
14
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(LOW-GAIN MODE)
MAX2645-01
15
SUPPLY CURRENT (mA)
MAX2645
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
0
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
15
20
RBIAS (kΩ)
_______________________________________________________________________________________
25
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
GAIN vs. FREQUENCY
(LOW-GAIN MODE)
15
-6
TA = +85°C
9
8
-14
3.5
-15
3.6
3.7
TA = +85°C
TA = +85°C
13.8
13.6
13.2
LOW-NOISE FIGURE CIRCUIT
3.5
3.6
13.0
3.7
3.8
LOW-NOISE FIGURE CIRCUIT
3.0
4.0
3.5
4.5
5.0
FREQUENCY (GHz)
SUPPLY VOLTAGE (V)
GAIN vs. SUPPLY VOLTAGE
(LOW-GAIN MODE)
GAIN STEP
vs. SUPPLY VOLTAGE
GAIN vs. RBIAS
(HIGH-GAIN MODE)
GAIN STEP (dB)
-8.5
TA = +25°C
-9.0
-9.5
TA = +85°C
-10.0
14.8
25.0
TA = -40°C
5.5
MAX2645-09
25.5
24.5
GAIN (dB)
-8.0
15.0
MAX2645-08
26.0
MAX2645-07
-7.5
TA = +25°C
24.0
23.5
VCC = 5V
14.6
14.4
TA = +85°C
VCC = 3.3V
23.0
TA = -40°C
14.2
22.5
-10.5
LOW-NOISE FIGURE CIRCUIT
3.5
4.0
LOW-NOISE FIGURE CIRCUIT
22.0
4.5
5.0
3.0
5.5
3.5
4.0
4.5
14.0
5.0
5.5
LOW-NOISE FIGURE CIRCUIT
15.0
17.5
20.0
22.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
RBIAS (kΩ)
GAIN vs. RBIAS
(LOW-GAIN MODE)
NOISE FIGURE vs. FREQUENCY
(HIGH-GAIN MODE)
NOISE FIGURE vs. FREQUENCY
(LOW-GAIN MODE)
19
18
4
NOISE FIGURE (dB)
-10.6
-10.8
-11.0
-11.2
20
VCC = 3.3V
-11.4
-11.6
25.0
MAX2645-12
VCC = 5V
-10.4
5
NOISE FIGURE (dB)
-10.2
MAX2645-11
-10.0
MAX2645-10
3.0
3
2
17
16
15
14
13
12
1
-11.8
-12.0
14.0
13.4
3.4
3.8
TA = +25°C
14.2
FREQUENCY (GHz)
-7.0
-11.0
TA = +25°C
-11
-13
3.4
GAIN (dB)
-10
-12
LOW-NOISE FIGURE CIRCUIT
14.4
-9
10
7
GAIN (dB)
GAIN (dB)
GAIN (dB)
12
11
14.6
TA = -40°C
-8
TA = +25°C
TA = -40°C
14.8
-7
TA = -40°C
14
13
15.0
GAIN (dB)
16
MAX2645-05
-5
MAX2645-04
17
GAIN vs. SUPPLY VOLTAGE
(HIGH-GAIN MODE)
MAX2645-06
GAIN vs. FREQUENCY
(HIGH-GAIN MODE)
11
LOW-NOISE FIGURE CIRCUIT
15.0
17.5
20.0
RBIAS (kΩ)
0
22.5
25.0
LOW-NOISE FIGURE CIRCUIT
3.4
3.5
3.6
FREQUENCY (GHz)
10
3.7
3.8
LOW-NOISE FIGURE CIRCUIT
3.4
3.5
3.6
3.7
3.8
FREQUENCY (GHz)
_______________________________________________________________________________________
5
MAX2645
Typical Operating Characteristics (continued)
(MAX2645 EV kit, VCC = +3.3V, RBIAS = 20kΩ, fRFIN = 3550MHz, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(MAX2645 EV kit, VCC = +3.3V, RBIAS = 20kΩ, fRFIN = 3550MHz, TA = +25°C, unless otherwise noted.)
INPUT IP3 vs. SUPPLY VOLTAGE
(LOW-GAIN MODE)
TA = -40°C
5.5
TA = +85°C
5.0
15.0
4.0
3.5
TA = +25°C
3.0
2.5
17.5
20.0
22.5
25.0
3.0
RBIAS (kΩ)
INPUT IP3 vs. RBIAS
(HIGH-GAIN MODE)
3.5
4.5
5.0
INPUT IP3 (dBm)
5
3
VCC = 3.3V
3.0
-3.5
MAX2645-17
13.5
13.0
11.5
17.5
20.0
22.5
25.0
15.0
17.5
20.0
MAX2645-19
TA = -40°C
-15
VCC = 5V
LOW-NOISE FIGURE CIRCUIT
6
-5.0
0
INPUT POWER (dBm)
4.5
5.0
2.50
LOW GAIN
2.25
5.5
1.75
-5
HIGH GAIN
1.50
-7
5.0
4.0
3.5
2.00
-4
VCC = 3.3V
-6
-10.0
LOW-NOISE FIGURE CIRCUIT
3.0
INPUT VSWR vs. FREQUENCY
1.25
-20
-25
-7.0
25.0
VSWR
INPUT P1dB (dBm)
TA = +25°C
-10
TA = +85°C
-6.5
SUPPLY VOLTAGE (V)
-2
-3
TA = +85°C
TA = +25°C
-6.0
-8.5
22.5
INPUT P1dB vs. RBIAS
(HIGH-GAIN MODE)
-5
-5.5
-8.0
LOW-NOISE FIGURE CIRCUIT
OUTPUT POWER vs. INPUT POWER
(LOW-GAIN MODE)
0
-5.0
-7.5
RBIAS (kΩ)
5
5.5
-4.5
VCC = 3.3V
RBIAS (kΩ)
10
TA = -40°C
-4.0
MAX2645-20
15.0
5.0
INPUT P1dB vs. SUPPLY VOLTAGE
(HIGH-GAIN MODE)
14.0
LOW-NOISE FIGURE CIRCUIT
4.5
INPUT IP3 vs. RBIAS
(LOW-GAIN MODE)
12.0
-1
4.0
3.5
SUPPLY VOLTAGE (V)
VCC = 5V
12.5
1
5.5
SUPPLY VOLTAGE (V)
14.5
VCC = 5V
LOW-NOISE FIGURE CIRCUIT
10.5
15.0
7
INPUT IP3 (dBm)
4.0
15.5
MAX2645-16
9
TA = +85°C
11.0
LOW-NOISE FIGURE CIRCUIT
INPUT P1dB (dBm)
15.0
1.0
12.5
11.5
1.5
LOW-NOISE FIGURE CIRCUIT
0
13.0
12.0
2.0
1
13.5
MAX2645-18
2
TA = +25°C
14.0
INPUT IP3 (dBm)
INPUT IP3 (dBm)
NOISE FIGURE (dB)
4.5
3
TA = -40°C
14.5
MAX2645-21
4
15.5
MAX2645-14
6.0
MAX2645-13
5
INPUT IP3 vs. SUPPLY VOLTAGE
(HIGH-GAIN MODE)
MAX2645-15
NOISE FIGURE vs. RBIAS
(HIGH-GAIN MODE)
OUTPUT POWER (dBm)
MAX2645
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
LOW-NOISE FIGURE CIRCUIT
15.0
17.5
20.0
RBIAS (kΩ)
1.00
22.5
25.0
LOW-NOISE FIGURE CIRCUIT
3.4
3.5
3.6
FREQUENCY (GHz)
_______________________________________________________________________________________
3.7
3.8
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
REVERSE ISOLATION (dB)
3.5
3.0
HIGH GAIN
2.5
15.5
-15
LOW GAIN
-20
HIGH GAIN
3.5
3.6
3.7
3.8
3.5
3.6
3.7
FREQUENCY (GHz)
-11.0
HIGH-INPUT IP3 CIRCUIT
4.5
-13.0
19
3.0
LOW GAIN
2.5
2.0
-14.0
HIGH GAIN
HIGH-INPUT IP3 CIRCUIT
15
14
TA = +25°C
3.5
3.6
3.7
10
3.4
3.8
3.5
3.6
3.7
3.8
PA PREDRIVER CIRCUIT
3.4
3.5
3.6
3.7
FREQUENCY (GHz)
FREQUENCY (GHz)
GAIN vs. FREQUENCY
(LOW-GAIN MODE)
GAIN vs. SUPPLY VOLTAGE
(HIGH-GAIN MODE)
GAIN vs. SUPPLY VOLTAGE
(LOW-GAIN MODE)
VCC = 5V
TA = -40°C
16.0
-7
GAIN (dB)
TA = +85°C
-10
TA = -40°C
TA = +25°C
15.0
14.5
TA = +25°C
TA = -40°C
-9.5
GAIN (dB)
-9
VCC = 5V
-9.0
TA = +25°C
15.5
-8
-8.5
MAX2645-29
MAX2645-28
16.5
3.8
MAX2645-30
FREQUENCY (GHz)
VCC = 5V
-11
TA = +85°C
11
1.0
-5
GAIN (dB)
TA = -40°C
16
12
1.5
-14.5
-6
VCC = 5V
13
3.4
3.8
17
-13.5
-15.0
MAX2645-24
20
GAIN (dB)
VSWR
-12.5
3.7
18
3.5
TA = -40°C
3.6
GAIN vs. FREQUENCY
(HIGH-GAIN MODE)
TA = +25°C
-12.0
3.5
FREQUENCY (GHz)
4.0
-11.5
GAIN (dB)
5.0
MAX2645-25
TA = +85°C
3.4
3.8
INPUT VSWR
vs. FREQUENCY
GAIN vs. FREQUENCY
(LOW-GAIN MODE)
-10.5
TA = +85°C
12.0
3.4
FREQUENCY (GHz)
-10.0
TA = +25°C
14.0
12.5
-35
3.4
14.5
13.0
-30
1.0
TA = -40°C
15.0
13.5
-25
2.0
1.5
HIGH-INPUT IP3 CIRCUIT
16.0
-10
GAIN (dB)
LOW GAIN
4.0
16.5
MAX2645-26
VSWR
4.5
LOW-NOISE FIGURE CIRCUIT
-5
5.0
17.0
MAX2645-23
LOW-NOISE FIGURE CIRCUIT
5.5
0
MAX2645-22
6.0
GAIN vs. FREQUENCY
(HIGH-GAIN MODE)
REVERSE ISOLATION vs. FREQUENCY
MAX2645-27
OUTPUT VSWR vs. FREQUENCY
TA = +85°C
-10.0
-10.5
14.0
-11.0
13.5
-11.5
TA = +85°C
-12
-13
13.0
-14
-15
PA PREDRIVER CIRCUIT
3.4
3.5
3.6
FREQUENCY (GHz)
12.5
3.7
3.8
-12.0
PA PREDRIVER CIRCUIT
3.0
3.5
4.0
-12.5
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
PA PREDRIVER CIRCUIT
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
7
MAX2645
Typical Operating Characteristics (continued)
(MAX2645 EV kit, VCC = +3.3V, RBIAS = 20kΩ, fRFIN = 3550MHz, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(MAX2645 EV kit, VCC = +3.3V, RBIAS = 20kΩ, fRFIN = 3550MHz, TA = +25°C, unless otherwise noted.)
OUTPUT POWER vs. INPUT POWER
(LOW-GAIN MODE)
12
TA = +25°C
10
TA = -40°C
INPUT VSWR vs. FREQUENCY
PA PREDRIVER CIRCUIT
3.5
4.0
-5
SUPPLY VOLTAGE (V)
5.0
5.5
PA PREDRIVER CIRCUIT
VCC = 5V
3.5
TA = +25°C
-10
3.0
LOW GAIN
2.5
-15
-25
4.5
4.5
TA = -40°C
2.0
HIGH GAIN
-20
3.0
5.0
4.0
0
TA = +85°C
8
7
VCC = 5V
5
OUTPUT POWER (dBm)
TA = +85°C
11
9
10
MAX2645-33
VCC = 5V
VSWR
13
MAX2645-32
OUTPUT P1dB POINT vs. SUPPLY VOLTAGE
(HIGH-GAIN MODE)
MAX2645-31
MAX2645
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
1.5
PA PREDRIVER CIRCUIT
-10.0
-5.0
1.0
0
5.0
INPUT POWER (dBm)
3.4
3.5
3.6
3.7
3.8
FREQUENCY (GHz)
Pin Description
8
PIN
NAME
FUNCTION
1, 2, 4, 7,
EP
GND
Ground. Connect to ground plane with a low-inductance connection. Solder exposed paddle evenly
to the board ground plane.
3
RFIN
RF Input Port to Amplifier. Requires a matching network and a DC-blocking capacitor that may be
part of this network. See Figure 1 for recommended component values.
5
BIAS
Bias-Setting Resistor Connection. A resistor, RBIAS, placed from BIAS to ground sets the linearity
and supply current of the amplifier.
6
RFOUT
RF Open-Collector Output Port of Amplifier. Requires a matching network composed of an
inductance to VCC and a DC-blocking capacitor. See Figure 1 for recommended component
values.
8
SHDN
Shutdown Control Logic-Level Input. A logic high enables the device for normal operation. A logic
low places the device in low-power shutdown mode.
9
GAIN
Gain Control Logic-Level Input. A logic high places the device in high-gain mode. A logic low
places the device in low-gain mode, reducing the gain by 25dB.
10
VCC
Power Supply Input. Bypass directly to ground with a capacitor as close to the supply pin as
possible. See Figure 1 for recommended component values.
_______________________________________________________________________________________
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
Gain Step Control
The MAX2645 features a logic-level gain step control
input (GAIN) that places the device in high-gain or lowgain mode. A logic-level high places the device in highgain mode, where the gain is 14.5dB. A logic-level low
places the device in low-gain/high-linearity mode, where
the gain is reduced to 10dB and the input IP3 performance is increased.
The MAX2645 is a versatile amplifier with high-gain,
high-linearity, and low-noise performance—features that
make it suitable for use as an LNA, high-linearity/lownoise amplifier, PA predriver, or LO buffer in the 3.4GHz
to 3.8GHz frequency range. See Figure 1, MAX2645
Typical Application Circuit, for recommended component values. A single external bias-setting resistor allows
the system designer to trade off linearity for reduced
supply current. A logic-level control reduces gain by a
25dB step to further improve input IP3 performance. A
low-power shutdown mode disables the device and
reduces current consumption to 0.1µA.
The MAX2645 features a logic-level shutdown control
input. A logic high on SHDN enables the device for normal operation. A logic low on SHDN disables all device
functions and reduces supply current to 0.1µA.
Bias Circuitry
Applications Information
The linearity and supply current of the MAX2645 are
externally programmable with a single resistor (RBIAS)
placed from BIAS to GND. Larger resistor values result
in lower IP3 performance and lower supply current, while
smaller resistor values result in higher IP3 performance
and higher supply current. Use resistor values in the
15kΩ to 25kΩ range, with a nominal value of 20kΩ
suitable for most applications. See Typical Operating
Characteristics for performance variation vs. R BIAS
value.
Shutdown Control
RF Input
The RFIN port is internally biased and requires an external DC-blocking capacitor. A matching network is
required for best performance. Figure 1 shows component values optimized for best noise-figure performance,
low-noise figure, high-input IP3 performance, and highoutput P1dB performance in the 3.4GHz to 3.8GHz frequency range. For matching to other frequencies, see
Tables 1 and 2.
Table 1. MAX2645 S-Parameters
FREQ
(MHz)
S11
MAG
S21
PHASE
MAG
S12
PHASE
MAG
S22
PHASE
MAG
PHASE
RBIAS = 20kΩ, VCC = +3.3V, TA = +25°C
3400
0.468
-149.8
5.061
-44.6
0.053
-55.5
0.660
-57.0
3450
0.466
-150.4
4.975
-46.3
0.058
-60.8
0.658
-58.4
3500
3550
0.472
0.469
-151.6
-153.4
5.098
4.883
-49.9
-53.7
0.056
0.054
-64.6
-62.7
0.661
0.658
-60.6
-63.0
3600
0.471
-154.6
4.814
-53.7
0.056
-64.4
0.647
-64.2
3650
0.477
-155.0
5.118
-57.4
0.058
-68.9
0.657
-66.2
3700
3750
0.485
0.484
-156.6
-156.5
4.769
4.780
-63.4
-62.3
0.054
0.058
-70.5
-72.0
0.657
0.654
-69.8
-70.9
3800
0.492
-157.0
4.939
-66.6
0.060
-75.4
0.654
-72.3
RBIAS = 15kΩ, VCC = +5V, TA = +25°C
3400
3450
0.454
0.457
-146.6
-147.4
5.350
5.245
-41.8
-43.5
0.057
0.061
-51.3
-56.7
0.651
0.646
-52.3
-53.7
3500
0.465
-147.9
5.375
-46.6
0.060
-61.2
0.654
-55.6
3550
0.468
-149.7
5.165
-50.3
0.057
-61.0
0.652
-58.3
3600
3650
0.472
0.481
-150.5
-150.5
5.066
5.386
-50.2
-53.4
0.060
0.063
-62.7
-67.6
0.645
0.652
-59.3
-60.7
3700
0.486
-152.2
5.040
-59.4
0.060
-67.8
0.648
-63.9
3750
0.486
-152.4
5.019
-58.3
0.062
-67.0
0.642
-64.8
3800
0.499
-152.6
5.207
-62.0
0.065
-73.3
0.643
-66.2
_______________________________________________________________________________________
9
MAX2645
Detailed Description
MAX2645
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
Table 2. MAX2645 Noise Parameters
|Γopt|
Γopt ANGLE
RN (Ω)
FREQUENCY (MHz)
FMIN (dB)
3400
2.098
0.237
144.1
31.1
3450
2.122
0.235
146.1
31.5
3500
2.148
0.235
148.2
32.0
3550
2.173
0.234
150.3
32.5
3600
2.198
0.233
152.4
32.9
3650
2.225
0.232
154.5
33.5
3700
2.251
0.231
156.5
33.9
3750
2.279
0.230
158.6
34.5
3800
2.306
0.229
160.7
35.0
3400
2.103
0.210
146.3
31.1
3450
2.127
0.209
148.4
31.6
3500
2.152
0.208
150.5
32.1
3550
2.177
0.207
152.6
32.5
3600
2.203
0.206
154.7
33.0
3650
2.229
0.206
156.8
33.5
3700
2.256
0.205
158.9
34.0
3750
2.282
0.204
161.0
34.6
3800
2.310
0.204
163.1
35.1
RBIAS = 20kΩ, VCC = +3.3V, TA = +25°C
RBIAS = 15kΩ, VCC = +5V, TA = +25°C
RF Output
The RFOUT port is an open-collector output that must be
tied to VCC through an inductance for proper biasing.
The MAX2645 EV kit uses a length of transmission line
equivalent to 1.5nH of inductance. A DC-blocking
capacitor is required and can be part of the output
matching network. See Figure 1 for component values
recommended for operation over the 3.4GHz to 3.8GHz
frequency range. See Table 1 for matching to other frequencies. This transmission line is terminated at the
VCC node with a radial stub for high-frequency bypassing. This arrangement provides a high-Q, low-loss bias
network used to optimize performance. The radial stub
can be replaced with an appropriate microwave
capacitor.
Power-Supply, Bias Circuitry, and LogicInput Bypassing
To minimize the amount of noise injected into the bias
circuitry and logic inputs, bypass the pins with capacitors located as near to the device pin as possible. For
additional isolation on the logic-control pins, place resistors between the logic-control inputs and the bypass
capacitors. See Figure 1 for recommended component
values; refer to MAX2645 EV kit manual for recommended board layout.
Layout Considerations
A properly designed PC board is an essential part of any
RF/microwave circuit. Keep RF signal lines as short as
possible to reduce losses, radiation, and inductance.
Use separate, low-inductance vias to the ground plane
for each ground pin. For best performance, solder the
exposed paddle on the bottom of the device package
evenly to the board ground plane.
Proper power-supply bypassing is essential for high-frequency circuit stability. Bypass VCC with 10µF, 0.1µF,
and 50pF capacitors located as close to the VCC pin as
possible.
10
______________________________________________________________________________________
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
VCC
GND
VCC
0.1µF
47pF
2
C1
RF INPUT
3.4GHz to 3.8GHz
MAX2645
1
GND
GAIN
9
HIGH GAIN
LOW GAIN
8
ON
OFF
MAX2645
3
RFIN
SHDN
GND
GND
Z1
4
7
RADIAL STUB *
40°
5
220pF
BIAS
RFOUT
TLINE
LEQUIV = 1.5nH
8
294
mil
s
VCC
1000pF
RF
OUTPUT
RBIAS
0.75pF
APPLICATION CIRCUIT
LNA, LOW NF
LNA, HIGH INPUT IP3
PA PREDRIVER
C1
Z1
1.5pF
1000pF
0.01µF
1.8nH
0.75pF
0.75pF
RBIAS (kΩ) VCC (V)
20
3.3
20
15
3.3
5.0
* BOARD MATERIAL = GETek, COPPER THICKNESS = 1 oz
BOARD THICKNESS = 0.012in, DIELECTRIC CONSTANT = 3.8
Figure 1. Typical Application Circuit
MAX2645
MAX2645
RF
IMAGE-REJECT
FILTER
MAX2683
MAX2684
IF
BANDPASS
FILTER
RECEIVE
IF OUTPUT
LOW NF
LNA
MAX2645
HIGH IP3
LNA
LO
LO BUFFER
DUPLEXER
MAX2645
MAX2645
RF
BANDPASS
FILTER
LO
LO BUFFER
TRANSMIT
IF INPUT
PA
MAX2683
MAX2684
PA PREDRIVER
Figure 2. Typical System Application Block Diagram
______________________________________________________________________________________
11
Pin Configuration
Chip Information
TRANSISTOR COUNT: 271
TOP VIEW
GND 1
10 VCC
GND
2
RFIN
3
9
GAIN
8
SHDN
GND
4
7
GND
BIAS
5
6
RFOUT
MAX2645
µMAX-EP
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
e
10LUMAX.EPS
MAX2645
3.4GHz to 3.8GHz SiGe
Low-Noise Amplifier/PA Predriver
4X S
10
10
INCHES
H
ÿ 0.50±0.1
0.6±0.1
1
1
0.6±0.1
BOTTOM VIEW
TOP VIEW
D2
MILLIMETERS
MAX
DIM MIN
A
0.043
A1
0.006
0.002
A2
0.030
0.037
D1
0.116
0.120
D2
0.114
0.118
E1
0.116
0.120
E2
0.114
0.118
H
0.187
0.199
L
0.0157 0.0275
L1
0.037 REF
b
0.007
0.0106
e
0.0197 BSC
c
0.0035 0.0078
0.0196 REF
S
α
0∞
6∞
MAX
MIN
1.10
0.15
0.05
0.75
0.95
3.05
2.95
2.89
3.00
3.05
2.95
2.89
3.00
4.75
5.05
0.40
0.70
0.940 REF
0.177
0.270
0.500 BSC
0.090
0.200
0.498 REF
0∞
6∞
E2
GAGE PLANE
A2
c
A
b
A1
α
E1
D1
L
L1
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 10L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0061
REV.
I
1
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.