MAXIM MAX2245

19-2204; Rev 0; 12/01
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
The MAX2244/MAX2245/MAX2246 single-supply, lowvoltage power amplifiers (PAs) are designed for 20dBm
Bluetooth™ Class 1 applications in the 2.4GHz to 2.5GHz
band. The MAX2244/MAX2245 deliver a peak output
power of 22dBm with greater than 20dB output-power
control range. The 22dBm output power compensates for
the filter loss between the PA and the antenna, allowing
20dBm to be delivered to the antenna. The MAX2246 provides a peak output power of 20dBm for a 30% reduction
in supply current.
The PAs integrate a power detector and closed-loop
power-control circuitry to provide nearly constant output
power over the full range of supply voltage, temperature,
and input power level. The voltage at the analog control
input precisely controls the output power level.
The MAX2244/MAX2245/MAX2246 feature a low-current
shutdown mode through a simple logic input. Internal circuitry automatically controls the ramp-up/down of the
output power level during turn-on and turn-off to meet
Bluetooth spurious emissions requirements.
The devices operate from a 3V to 3.6V single supply.
The MAX2244/MAX2246 have a power-control voltage
range of 0.5V to 2V, and the MAX2245 has a control
voltage range of 0.9V to 2.2V. The devices are packaged in a miniature ultra chip-scale package (UCSP™),
significantly reducing the required board area.
Applications
Bluetooth Class 1 Radios
802.11 FHSS/HomeRF™ Radios
Features
♦ 2.4GHz to 2.5GHz Operation
♦ Accurate Closed-Loop Output Power Control
Over Full Temperature, Supply, and Input Power
Range
♦ Convenient Analog Power-Control Interface
♦ 22dBm Peak Output Power (MAX2244/MAX2245)
♦ 20dBm Peak Output with 30% Reduced Supply
Current (MAX2246)
♦ Internal Bandwidth-Limited Power Ramping
♦ 50Ω Integrated Input Match
♦ 0.5µA Shutdown Supply Current
♦ Ultra Chip-Scale Package (1.56mm ✕ 1.56mm)
Ordering Information
TEMP
RANGE
PART
BUMP
PACKAGE
TOP
MARK
MAX2244EBL-T
-40°C to +85°C
9 UCSP*-9
AAP
MAX2245EBL-T
-40°C to +85°C
9 UCSP*-9
AAQ
MAX2246EBL-T
-40°C to +85°C
9 UCSP*-9
AAY
*UCSP reliability is integrally linked to the user's assembly
methods, circuit board material, and environment. See the
UCSP Reliability Notice in the UCSP Reliability section of this
data sheet for more information.
Pin Configuration appears at end of data sheet.
2.4GHz Cordless Phones
Functional Diagram
VCC1
VCC2
C2
SHUTDOWN
RFIN/
SHDN
B1
BIAS
MATCH
MATCH
A1
B3
MATCH
CONTROL
AMP
MAX2244
MAX2245
MAX2246
PC
A2
RFOUT
POWER
DETECTOR
ANALOG
INTERFACE
C3
GND
C1
GND
Bluetooth is a trademark of Ericsson Corp.
B2
GND
A3
GND
HomeRF is a trademark of The HomeRF Working Group.
UCSP is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ 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
MAX2244/MAX2245/MAX2246
General Description
MAX2244/MAX2245/MAX2246
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
ABSOLUTE MAXIMUM RATINGS
VCC1, VCC2, RFOUT to GND .................................-0.3V to +6.0V
RFIN/SHDN, PC to GND.............................-0.3V to (VCC + 0.3V)
RF Input Power (RFIN)....................................................+10dBm
Load Mismatch (VSWR) Without Damage ..............................6:1
Continuous Power Dissipation (TA = +85°C)
9-Pin UCSP (derate 8.8mW/°C above TA = +85°C).....700mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature .....................................................+150°C
Storage Temperature Range .............................-65°C to +150°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.
DC ELECTRICAL CHARACTERISTICS
(Typical Application Circuit, VCC = 3V to 3.6V, no RF signals applied, V SHDN ≥ 2V, VPC = 0, TA = -40°C to +85°C, unless otherwise
noted. Typical values are at VCC = 3V, TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
CONDITIONS
Supply Voltage
MIN
TYP
3.0
VPC = 0.5V, TA = +25°C
MAX2244
PRFIN = 0 to 4dBm,
2.45GHz
65
VPC = 0.5V, TA = -40°C to +85°C
VPC = 2V, TA = +25°C
172
179
195
93
VPC = 2.2V, TA = +25°C
42
118
2
140
144
0.5
10
2.0
SHDN Input Voltage Low
PC Input Current
55
61
SHDN = GND
SHDN Input Current
Active control range
mA
208
VPC = 0.5V, TA = +25°C
MAX2246
VPC = 0.5V, TA = -40°C to +85°C
PRFIN = 0 to 4dBm,
VPC = 2V, TA = +25°C
2.45GHz
VPC = 2V, TA = -40°C to +85°C
PC Input Voltage Range
200
87
VPC = 0.9V, TA = -40°C to +85°C
SHDN Input Voltage High
V
83
65
VPC = 2.2V, TA = -40°C to +85°C
Shutdown Supply Current
3.6
205
VPC = 0.9V, TA = +25°C
Supply Current (Note 2)
UNITS
98
VPC = 2V, TA = -40°C to +85°C
MAX2245
PRFIN = 0 to 4dBm,
2.45GHz
MAX
V
0.6
V
µA
-1
1
MAX2244/MAX2246
0.5
2.0
MAX2245
0.9
2.5
MAX2244/MAX2246, VPC = 0 to 2.5V
-15
5
MAX2245, VPC = 0 to 3V
-20
10
_______________________________________________________________________________________
µA
V
µA
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
(Typical Application Circuit, VCC = 3V, PRFIN = 0 to 4dBm, fRFIN = 2.45GHz, 50Ω system, V SHDN ≥ 2V, TA = +25°C, unless otherwise
noted. Typical values are at VCC = 3V, PRFIN = 2dBm, fRFIN = 2.45GHz, TA = +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
Frequency Range (Note 3)
MIN
TYP
2.4
Input Power
0
MAX2244, VPC = 0.5V
MAX2244, VPC = 2V
MAX2245, VPC = 0.9V
Output Power (Note 2)
MAX2245, VPC = 2.2V
MAX2246, VPC = 0.5V
MAX2246, VPC = 2V
Harmonic Output (Notes 2, 4)
Shutdown Mode Output (Note 2)
In-Band Spurious (Notes 2, 3, 5)
PRFOUT at any level
MAX
UNITS
2.5
GHz
4
dBm
TA = +25°C
0
4
7
TA = +25°C
20.5
22.0
23.5
TA = -40°C to +85°C
20
TA = +25°C
0
4
7
TA = +25°C
20.5
22.0
23.5
TA = -40°C to +85°C
24
20
dBm
24
TA = +25°C
-4.5
0.5
5.5
TA = +25°C
19
20
21
TA = -40°C to +85°C
17
21
MAX2244/MAX2245
-7
-1
MAX2246
-16
-13
V SHDN ≤ 0.6V, PRFIN = 4dBm
-30
Frequency offset = ±500kHz
-20
Frequency offset = ±1.5MHz
-20
Frequency offset = ±2.5MHz
-40
Nonharmonic Spurious Output
(Note 2)
All power levels, load VSWR ≤ 3:1
Power Ramp Turn-On Time
(Notes 2, 6)
MAX2244/MAX2246, VPC steps from 0 to 2V
4
MAX2245/MAX2246, VPC steps from 0 to 2.5V
4
Power Ramp Turn-Off Time
(Notes 2, 7)
MAX2244, VPC steps from 2V to 0
1.8
MAX2245, VPC steps from 2.5V to 0
1.8
Input VSWR (Note 2)
RS = 50Ω, over full PRFIN range
dBm
dBc
dBm
-30
1.5:1
dBm
dBm
µs
µs
2:1
Note 1: Limits are 100% production tested at TA = +25°C. Limits over the entire operating temperature range are guaranteed by
design and characterization, but are not production tested.
Note 2: Guaranteed by design and characterization.
Note 3: Assumes the output is optimally matched to cover the 2.4GHz to 2.5GHz band.
Note 4: Valid for the case in which the output stage is matched with a two-section transmission line, lowpass matching network to
minimize the 2nd and 3rd harmonics, as shown in the Typical Application Circuit.
Note 5: Output measured in a 100kHz RBW. Power on/off duty cycle = 50%. Test signal: GFSK, BT = 0.5, 1 bit/symbol, 1Mbps,
frequency deviation = 175kHz.
Note 6: The total turn-on and settling time required for the PA output power to settle to within ±1dB of the final value.
Note 7: The total turn-off time for the PA output power to drop to -10dBm.
_______________________________________________________________________________________
3
MAX2244/MAX2245/MAX2246
AC ELECTRICAL CHARACTERISTICS
Typical Operating Characteristics
(Typical Application Circuit, VCC = 3V, TA = +25°C, PRFIN = 2dBm, fRFIN = 2.45GHz, SHDN = VCC, unless otherwise noted.)
TA = +25°C
-10
VCC = 4V
VCC = 3V
10
0
150
TA = +85°C
100
TA = +25°C
TA = -40°C
50
-10
TA = -40°C
200
SUPPLY CURRENT (mA)
0
MAX2244-46 toc02
MAX2244-46 toc01
TA = +85°C
10
20
OUTPUT POWER (dBm)
OUTPUT POWER (dBm)
20
MAX2244 SUPPLY CURRENT
vs. POWER CONTROL (VPC)
MAX2244
OUTPUT POWER vs. POWER CONTROL (VPC)
MAX2244-46 toc03
MAX2244
OUTPUT POWER vs. POWER CONTROL (VPC)
VCC = 5.0V
-20
0.5
1.0
1.5
2.0
0
0
2.5
0.5
1.0
1.5
2.0
0
2.5
0.5
1.0
2.0
VPC (V)
VPC (V)
MAX2244
OUTPUT POWER vs. FREQUENCY
MAX2244
OUTPUT POWER vs. INPUT POWER
MAX2244
HARMONIC OUTPUT SPECTRUM
VPC = 2.0V
20
VPC = 1.0V
15
10
25
MAX2244-46 toc05
MAX2244-46 toc04
25
VPC = 2V
20
2.5
VPC = 2V
0dBm
VPC = 1V
15
10dB/div
5fO
10
fO
2fO
3fO
4fO
VPC = 0.5V
VPC = 0.5V
5
5
0
0
2.40
2.42
2.44
2.46
2.48
-15
2.50
-10
-5
0
5
0.1
MAX2244
FSK MODULATED OUTPUT SPECTRUM
MAX2244
POWER-ON/OFF CHARACTERISTICS
20
OUTPUT POWER (dBm)
0dBm
10dB/div
MAX2244-46 toc08
30
MAX2244-46 toc07
VPC = 2V
13
FREQUENCY (GHz)
INPUT POWER (dBm)
FREQUENCY (GHz)
10
PRFOUT
5
4
VSHDN
0
3
-10
2
-20
1
-30
0
VSHDN (V)
-40
2.45GHz
0.5MHz/div
4
1.5
VPC (V)
OUTPUT POWER (dBm)
0
MAX2244-46toc06
-20
OUTPUT POWER (dBm)
MAX2244/MAX2245/MAX2246
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
TIME (2µs/div)
_______________________________________________________________________________________
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
TA = +25°C
-10
10
TA = +85°C
VCC = 3V
0
150
100
TA = -40°C
TA = -40°C
0.5
1.0
1.5
2.0
2.5
0
3.0
0.5
1.0
1.5
2.0
2.5
0
3.0
0.5
1.0
1.5
2.0
2.5
VPC (V)
VPC (V)
VPC (V)
MAX2245
OUTPUT POWER vs. FREQUENCY
MAX2245
OUTPUT POWER vs. INPUT POWER
MAX2245
HARMONIC OUTPUT SPECTRUM
VPC = 2.5V
20
VPC = 2.5V
20
OUTPUT POWER (dBm)
VPC = 1.5V
15
10
VPC = 1V
MAX2244-46 toc13
25
MAX2244-46 toc12
25
3.0
VPC = 2.2V
VPC = 1.5V
0dBm
15
10dB/div
5fO
10
fO
2fO
3fO
4fO
VPC = 1V
5
5
0
0
2.44
2.46
2.48
2.50
-15
-10
FREQUENCY (GHz)
-5
0.1
5
0
FREQUENCY (GHz)
INPUT POWER (dBm)
MAX2245
FSK MODULATED OUTPUT SPECTRUM
VPC = 2.2V
0dBm
10dB/div
13
SHUTDOWN CURRENT vs. TEMPERATURE
800
MAX2244-46 toc16
2.42
SHUTDOWN CURRENT (nA)
2.40
MAX2244-46 toc15
OUTPUT POWER (dBm)
0
-20
0
TA = +25°C
50
-10
-20
MAX2244-46 toc11
VCC = 4V
VCC = 5V
200
SUPPLY CURRENT (mA)
TA = +85°C
MAX2244-46 toc10
MAX2244-46 toc09
10
0
20
OUTPUT POWER (dBm)
OUTPUT POWER (dBm)
20
MAX2245
SUPPLY CURRENT vs. POWER CONTROL (VPC)
MAX2245
OUTPUT POWER vs. POWER CONTROL (VPC)
MAX2244/45 toc14
MAX2245
OUTPUT POWER vs. POWER CONTROL (VPC)
600
400
200
0
2.45GHz
0.5MHz/div
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
_______________________________________________________________________________________
5
MAX2244/MAX2245/MAX2246
Typical Operating Characteristics (continued)
(Typical Application Circuit, VCC = 3V, TA = +25°C, PRFIN = 2dBm, fRFIN = 2.45GHz, SHDN = VCC, unless otherwise noted.)
Typical Operating Characteristics (continued)
(Typical Application Circuit, VCC = 3V, TA = +25°C, PRFIN = 2dBm, fRFIN = 2.45GHz, SHDN = VCC, unless otherwise noted.)
0
VCC = 4V
VCC = 3V
0
150
TA = +85°C
100
TA = +25°C
50
-10
TA = +25°C
MAX2244-46 toc19
VCC = 5V
10
200
SUPPLY CURRENT (mA)
10
-10
MAX2244-46 toc18
TA = +85°C
20
OUTPUT POWER (dBm)
OUTPUT POWER (dBm)
20
MAX2246 SUPPLY CURRENT
vs. POWER CONTROL (VPC)
MAX2246
OUTPUT POWER vs. POWER CONTROL (VPC)
MAX2244-46 toc017
MAX2246
OUTPUT POWER vs. POWER CONTROL (VPC)
TA = -40°C
TA = -40°C
-20
0.5
1.0
1.5
2.0
0.5
1.0
1.5
2.0
MAX2246
OUTPUT POWER vs. FREQUENCY
MAX2246
OUTPUT POWER vs. INPUT POWER
VPC = 1V
10
20
5
0.5
1.0
1.5
VPC = 2V
2.5
VPC = 2V
0dBm
15
VPC = 1V
10dB/div
5fO
10
fO
2fO
3fO
4fO
5
VPC = 0.5V
VPC = 0.5V
0
0
2.42
2.44
2.46
2.48
2.50
-10
-15
FREQUENCY (GHz)
-5
0
5
0.1
MAX2246
FSK MODULATED OUTPUT SPECTRUM
10dB/div
1: -20.322dB AT 2.4GHz
2: -13.482dB AT 2.5GHz
-5
S11 MAGNITUDE (dB)
0dBm
S11 OF RFIN
0
MAX2244-46 toc23
VPC = 2V
13
FREQUENCY (GHz)
INPUT POWER (dBm)
-10
MAX2244-46 toc24
2.40
2
-15
-20
1
-25
-30
2.45GHz
0.5MHz/div
6
2.0
MAX2246
HARMONIC OUTPUT SPECTRUM
25
MAX2244-46 toc20
VPC = 2V
0
2.5
VPC (V)
VPC (V)
OUTPUT POWER (dBm)
15
0
0
VPC (V)
25
20
2.5
MAX2244-46 toc21
0
MAX2244-46 toc22
-20
OUTPUT POWER (dBm)
MAX2244/MAX2245/MAX2246
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0
FREQUENCY (GHz)
_______________________________________________________________________________________
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
PIN
NAME
DESCRIPTION
A1
PC
Power-Control Voltage Input. Adjust PC between 0.5V and 2V (MAX2244/MAX2246) or 0.9V to
2.2V (MAX2245) to adjust output power. Drive PC below 0.3V to shut down the control loop
and put the device in standby mode.
A2
VCC2
DC Supply-Voltage Connection for the 2nd Stage
A3, B2, C1, C3
GND
Ground Connection. Connect to the PC board ground plane. Provide inductance connection
as low as is practical to the ground plane.
B1
RFIN/SHDN
RF Input and Digital Shutdown Control Input. RF path internally DC blocked and matched to
50Ω. Digital shutdown path is connected to the bias circuitry through a resistor.
B3
RFOUT
C2
VCC1
PA Open-Collector Output. Requires external pullup inductance for VCC bias and external
matching network for optimum output power and efficiency.
DC Supply-Voltage Connection for the 1st Stage, Bias, and Control Circuitry
Detailed Description
The MAX2244/MAX2245/MAX2246 are nonlinear PAs
guaranteed to operate over a 2.4GHz to 2.5GHz frequency range from a 3V to 3.6V single supply. The
MAX2244/MAX2245 provide 22dBm output power, and
the MAX2246 provides 20dBm output power at the
highest power setting. The signal path consists of three
amplifier stages: an input amplifier stage with
adjustable gain, and two fixed-gain amplifier stages.
The PAs have a dual-function input (RFIN/SHDN) for
the RF input signal and shutdown control. The shutdown function is controlled with CMOS level signals,
with a logic low putting the PA into low-current shutdown. The RF input is internally matched to 50Ω, eliminating the need for external matching.
The MAX2244/MAX2245/MAX2246 have interstage
matching to optimize output power and efficiency. The last
amplifier stage is open collector using an external pullup
inductor or RF choke. The output match for the PAs also
acts as a lowpass filter that attenuates harmonics.
These PAs provide closed-loop power control to provide a stable output power with variations in temperature, VCC, and RF input power. The control amplifier
varies the gain of the first stage to equalize the powercontrol voltage and the internal power-detector output.
The MAX2244/MAX2246 have a 0.5V to 2V power-control voltage range, and the MAX2245 has a 0.9V to 2.2V
power-control voltage range.
The internal bias circuit provides separate bias voltages and currents to the amplifier stages. An internal
lowpass RC filter isolates the bias currents, preventing
them from being corrupted by the RF signals. The bias
circuit design also ensures the stability of the PA when
connected to high VSWR loads over all power levels.
Applications Information
Power-Supply Connections
The MAX2244/MAX2245/MAX2246 are designed to operate from a single, positive supply voltage (VCC) with three
connections made to VCC: VCC1, VCC2, and RFOUT bias.
Join the VCC traces together using a star layout, which
reduces crosstalk and promotes stable operation. At the
common point of the star, connect 10µF and 10nF decoupling capacitors to ground to reduce noise and handle
current transients. Additionally, each leg requires a highfrequency bypass capacitor and a 1nF power-supply
decoupling capacitor near the IC.
High-frequency bypass capacitors are required close
to the IC. For VCC1, connect a capacitor approximately
1mm from the VCC1 pad. The distance of the capacitor
from the pad affects the impedance at VCC1, which
affects output power of the first stage. For optimal output power from stage 1, VCC1 requires 0.3nH to 0.4nH
inductance.
The output power of the second stage is affected by the
impedance presented to VCC2, which is controlled by
the distance between the VCC2 pad and its bypass
capacitor. For optimal electrical distance, see Figure 1
and Table 1.
RFOUT must be pulled up to VCC through an inductor
or an inductive transmission line. If using a transmission
line, a high-frequency bypass capacitor from VCC to
ground is necessary to terminate the transmission line
and set its electrical length. The inductance formed by
the length of the transmission line is part of the outputmatching network, and therefore is critical. See the
Output Matching section for more information on
RFOUT requirements.
_______________________________________________________________________________________
7
MAX2244/MAX2245/MAX2246
Pin Description
MAX2244/MAX2245/MAX2246
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
VCC
C1
10µF
C2
10nF
C4
27pF
TRANSCEIVER IC
T4
C3
1nF
DAC
T1
PC
VCC2
GND
A1
A2
A3
RFIN/
SHDN
GND
RFOUT
B1
B2
B3
GND
VCC1
GND
C1
C2
C3
R2
2.5kΩ
RFIN
C5
10pF
R2
1kΩ
SHDN
MAX2244
MAX2245
MAX2246
C10
C6
C11
1nF
T2
RFOUT
C7
T3
C8
C9
1nF
Figure 1. MAX2244/MAX2245/MAX2246 Typical Application Circuit
Table 1. Typical Application Circuit
Component Values
COMPONENT
MAX2244
MAX2245
C6
10pF
5.6pF
MAX2246
10pF
C7
1.2pF
1.2pF
1.3pF
C8
5pF
5pF
27pF
C10
100pF
100pF
27pF
T1
50Ω, 17.6°
50Ω, 18°
50Ω, 25°
T2
50Ω, 50°
50Ω, 53°
50Ω, 50°
T3
50Ω, 5.3°
50Ω, 5.3°
50Ω, 5.3°
T4
50Ω, 5.3°
50Ω, 5.9°
50Ω, 8.9°
Place the 1nF power-supply decoupling capacitors
between the star connection and the smaller bypass
capacitors and close to the IC. Larger trace lengths
between the decoupling capacitors and the IC increase
the parasitic trace inductance, which, when combined
with the capacitors on VCC1 and VCC2, can form an LC
tank and introduce instability in the MHz range. If this
happens, you can add a small-value resistor (~10Ω),
between the 1nF capacitor and ground to de-Q the
capacitor and dampen the oscillation.
Note: Electrical lengths given for 2.4GHz.
8
_______________________________________________________________________________________
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
Output Matching
The output structure of these nonlinear PAs is an opencollector transistor that requires external impedance
matching and pullup inductance for biasing. The recommended output matching network is shown in the Typical
Application Circuits (Figure 1). The impedance presented
to the RFOUT pin is shown in Figure 2 and Table 2. This
impedance is specified relative to a reference plane at
the amplifier output into the matching network and load.
The matching network is for impedance transformation
that transforms 6Ω to 50Ω with the specified maximum
output power. The network also forms a lowpass filter that
provides attenuation for the 2nd and 3rd harmonics. A
shunt capacitor (C7) is needed to perform the transformation, and the inductive 50Ω transmission line (T2) is needed to match that capacitance. A larger capacitor can be
used to increase the maximum output power, but the
transmission line also must be increased to maintain a
match with C7. A DC-blocking capacitor (C6) of 5pF to
10pF is necessary between the PA output and the transmission line.
The pullup inductance from RFOUT to VCC serves three
main purposes: it resonates out the capacitive PA output,
provides biasing for the output stage, and becomes a
high-frequency choke to reduce RF energy from coupling
into VCC. The pullup inductance normally is a 50Ω transmission line (T1); however, chip inductors can be used
instead. The typical application circuit terminates the
transmission line with a capacitor (C6).
MATCHING IMPEDANCE FOR RFOUT PIN
SMITH CHART
MAX2244: 6.26Ω +j13.56Ω AT 2.45GHz
MAX2245: 6.35Ω +j13.25Ω AT 2.45GHz
MAX2246: 5.50Ω +j13.50Ω AT 2.45GHz
Figure 2. Impedance of Matching Network at RFOUT Pin
Table 2. Matching Network Impedance
MAX2244
FREQUENCY
REAL
IMAG
GHz
(Ω)
(Ω)
MAX2245
MAX2246
REAL IMAG REAL IMAG
(Ω)
(Ω)
(Ω)
(Ω)
2.40
6.47
13.2
6.61
12.94
5.73
13.01
2.45
6.26
13.5
6.35
13.25
5.50
13.50
2.50
6.06
13.9
6.11
13.59
5.27
14.02
Analog Power Control (PC)
The PAs use a closed-loop power-control system for
consistent output power across input power, supply voltage, and temperature. Output power is internally monitored and compared to the desired setting on PC. The
control amplifier then adjusts the first-stage variable-gain
amplifier until the output power matches the desired setting. The result is that the output power is controlled by
the voltage applied to PC.
The power-control voltage range at PC for the
MAX2244/MAX2246 is 0 to 2V. Output power remains at
its minimum for VPC between 0 and 0.4V. At approximately 0.4V, output power increases exponentially until
VPC = 2V, where output power is 22dBm (MAX2244) or
20dBm (MAX2246). See Figures 3a and 3c for the relationship between V PC and output power for the
MAX2244 and MAX2246, respectively.
Likewise, the MAX2245 output power is controlled by
VPC, but with a different power-control range. The powercontrol voltage range of the MAX2245 is 0 to 2.2V, with
output power beginning to increase when VPC = 0.9V.
Figure 3b shows the VPC and output power relationship
for the MAX2245.
_______________________________________________________________________________________
9
MAX2244/MAX2245/MAX2246
RF Input/SHDN
RFIN/SHDN is a dual-function input for a 2.4GHz to
2.5GHz RF signal and a DC-coupled shutdown function.
The input port is internally matched to 50Ω, making it
simple to interface the PAs to a 50Ω source without
external matching components. The PAs are designed to
amplify input signal levels of 0 to 4dBm, and although
the PAs function for input signals outside this range, output power and efficiency degrade. Note: Ensure that the
RF signal is present at the input when the PA is enabled.
If the RF signal is not present at startup, the PA functions
like any closed-loop control system and automatically
goes into a high-gain state, amplifying and transmitting
noise. Avoid this mode of operation.
The second function of the RFIN/SHDN is shutdown control. A DC voltage at the input port digitally controls the
on/off state with standard CMOS levels. The PA is in lowcurrent shutdown when the DC voltage is a valid logic
low and is active for a valid logic high. Connect the
SHDN signal to the RFIN/SHDN through a 1kΩ resistor.
Connect the RF signal to the RFIN/SHDN with a 10pF
capacitor in series to block any DC from corrupting the
SHDN signal.
MAX2244/MAX2245/MAX2246
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
MAX2244 TYPICAL OUTPUT POWER
POUT vs. VPC
25
20
15
POUT (dBm)
10
5
0
-5
-10
-15
-20
0
0.50
1.00
1.50
2.00
2.50
VPC (V)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
0
-9.45
0.42
-3.24
0.54
5.59
0.90
13.76
1.70
20.79
0.30
-9.45
0.43
-1.85
0.56
6.35
0.95
14.45
1.80
21.24
0.32
-9.45
0.44
-0.64
0.58
7.04
1.00
15.10
1.90
21.63
0.36
-9.50
0.45
0.43
0.60
7.67
1.10
16.25
2.00
21.91
0.37
-9.55
0.46
1.24
0.65
9.05
1.20
17.26
2.10
22.07
0.38
-10.79
0.47
1.97
0.70
10.22
1.30
18.16
2.20
22.08
0.39
-15.60
0.48
2.62
0.75
11.26
1.40
18.95
2.30
22.09
0.40
-8.65
0.50
3.79
0.80
12.19
1.50
19.65
2.40
22.10
0.41
-5.41
0.52
4.75
0.85
13.01
1.60
20.26
2.50
22.11
Figure 3a. MAX2244 Typical Output Power vs. Power-Control Voltage
10
______________________________________________________________________________________
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
MAX2244/MAX2245/MAX2246
MAX2245 TYPICAL OUTPUT POWER
POUT vs. VPC
25
20
15
POUT (dBm)
10
5
0
-5
-10
-15
-20
0
0.50
1.00
1.50
2.00
2.50
VPC (V)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
20.27
0
-8.00
0.90
0.91
0.99
6.90
1.80
0.82
-8.00
0.91
1.91
1.00
7.33
1.90
20.79
0.83
-8.14
0.92
2.78
1.10
10.64
2.00
21.22
0.84
-8.46
0.93
3.50
1.20
12.99
2.10
21.59
0.85
-17.51
0.94
4.20
1.30
14.84
2.20
21.91
0.86
-8.00
0.95
4.83
1.40
16.33
2.30
22.15
0.87
-4.13
0.96
5.39
1.50
17.61
2.40
22.20
0.88
-1.90
0.97
5.93
1.60
18.70
2.50
22.20
0.89
-0.35
0.98
6.44
1.70
19.59
—
—
Figure 3b. MAX2245 Typical Output Power vs. Power-Control Voltage
______________________________________________________________________________________
11
MAX2244/MAX2245/MAX2246
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
MAX2246 TYPICAL OUTPUT POWER
POUT vs. VPC
25
20
15
POUT (dBm)
10
5
0
-5
-10
-15
-20
0
0.50
1.00
1.50
2.00
2.50
VPC (V)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
VPC (V)
POUT
(dBm)
0
-17.80
0.40
-16.00
0.49
-0.31
1.00
12.26
1.90
19.48
0.10
-17.80
0.41
-11.80
0.50
0.30
1.10
13.43
2.00
19.95
14.60
0.20
-17.80
0.42
-8.74
0.51
2.75
1.20
2.10
20.33
0.30
-17.78
0.43
-6.65
0.52
4.75
1.30
15.39
2.20
20.66
0.35
-17.65
0.44
-5.02
0.53
6.03
1.40
16.21
2.30
20.81
0.36
-17.60
0.45
-3.67
0.54
7.26
1.50
16.97
2.40
20.82
0.37
-17.53
0.46
-2.65
0.55
8.35
1.60
17.67
2.50
20.82
0.38
-17.44
0.47
-1.78
0.56
9.28
1.70
18.31
—
—
0.39
-17.49
0.48
-1.02
0.57
10.89
1.80
18.93
—
—
Figure 3c. MAX2246 Typical Output Power vs. Power-Control Voltage
12
______________________________________________________________________________________
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
Use a star connection for the power-supply traces that
connect to VCC1, VCC2, and RFOUT. At a common point
of the power-supply traces, connect 10nF and 10µF
decoupling capacitors to ground. Place 1nF capacitors
closer to the IC on each VCC trace with the small value
matching capacitors closest to the IC. The distance of
the matching capacitors from the IC is critical. See the
Power Supply Connections section for more information.
The layout of the output section is important because
50Ω traces are used as part of the matching. See the
Output Matching section for component information.
The 50Ω traces can be bent, but be aware of how the
characteristics of the transmission line change, and
compensate for them accordingly.
Use a 50Ω line to directly connect to the input. Place
one pad of the 1kΩ resistor for the SHDN signal directly
on the 50Ω line or as close to the line as possible. Any
trace connected to the 50Ω line changes the line’s
characteristic impedance, causing power loss. The layout of the trace connecting PC is noncritical.
The chip-scale IC package uses a bump pitch of
0.5mm (19.7mil) and a bump diameter of 0.3mm
(~12mil). Therefore, lay out the solder pad spacing on
0.5mm (19.7mil) centers. Use a pad size of 0.25mm
(~10mil) and a solder mask opening of 0.33mm (13mil).
Round or square pads are permissible. Refer to the
Maxim document, Wafer Level Ultra-Chipscale
Packaging, for detailed information on UCSP layout and
handling.
Prototype Chip Installation
Alignment keys on the PC board around the chip are
helpful in prototype assembly. The MAX2244 and
MAX2246 EV kit PC boards have L-shaped alignment
keys at the diagonal corners of the chip. Align the chip
on the board before any other components are placed,
and place the board on a hotplate or hot surface until the
solder starts melting. Remove the board from the hotplate without disturbing the position of the chip. Let it
cool to room temperature before further processing the
board.
Pin 1 ID
A A A
AAA: Product ID Code
X X X
XXX: Lot Code
UCSP Reliability
The UCSP is a unique package that greatly reduces
board space compared to other packages. UCSP reliability is integrally linked to the user’s assembly methods, circuit board material, and usage environment.
Closely review these areas when considering using a
UCSP.
Performance through operating life test and moisture
resistance remains uncompromised as they are primarily
determined by the wafer-fabrication process.
Mechanical stress performance is a greater consideration for a UCSP. UCSP solder-joint contact integrity must
be considered because the package is attached through
direct solder contact to the user’s PC board. Testing to
characterize the UCSP reliability performance shows that
it is capable of performing reliably through environmental
stresses. Results of environmental stress tests and additional usage data and recommendations are detailed in
the UCSP application note, available on Maxim’s website, www.maxim-ic.com.
Chip Information
TRANSISTOR COUNT: 727
PROCESS: Bipolar
Pin Configuration
TOPVIEW
(BUMPS AT THE BOTTOM)
A
B
C
1
2
3
PC
VCC2
GND
A1
A2
A3
RFIN/
SHDN
GND
RFOUT
B1
B2
B3
GND
VCC1
GND
C1
C2
C3
UCSP
______________________________________________________________________________________
13
MAX2244/MAX2245/MAX2246
Marking Information
Layout
A good layout is necessary to achieve high-output power
with good efficiency. A solid ground plane must be used,
with any free board space also being grounded.
Connect any ground planes using multiple vias and lowinductance connections. Parasitic inductance reduces
output power and efficiency, so place the ground return
of the chip components as close to the IC as possible.
The MAX2244 EV kit and MAX2246 EV kit PC boards use
via-on-pad for low-inductance connections.
2.5GHz, 22dBm/20dBm Power Amplifiers with
Analog Closed-Loop Power Control
9LUCSP, 3x3.EPS
MAX2244/MAX2245/MAX2246
Package Information
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.