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19-2204; Rev 1; 2/03
2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control
General Description
The MAX2244/MAX2245/MAX2246 single-supply, lowvoltage power amplifiers (PAs) are designed for 20dBm BluetoothTM 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 (UCSPTM), significantly reducing the required board area. o 2.4GHz to 2.5GHz Operation o Accurate Closed-Loop Output Power Control Over Full Temperature, Supply, and Input Power Range o Convenient Analog Power-Control Interface o 22dBm Peak Output Power (MAX2244/MAX2245) o 20dBm Peak Output with 30% Reduced Supply Current (MAX2246) o Internal Bandwidth-Limited Power Ramping o 50 Integrated Input Match o 0.5A Shutdown Supply Current o Ultra Chip-Scale Package (1.56mm 1.56mm)
Features
MAX2244/MAX2245/MAX2246
Ordering Information
PART MAX2244EBL-T MAX2245EBL-T MAX2246EBL-T TEMP RANGE -40C to +85C -40C to +85C -40C to +85C BUMP PACKAGE 9 UCSP*-9 9 UCSP*-9 9 UCSP*-9 TOP MARK AAP AAQ AAY
Applications
Bluetooth Class 1 Radios 802.11 FHSS/HomeRFTM Radios 2.4GHz Cordless Phones
*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.
Functional Diagram
VCC1 C2 SHUTDOWN BIAS VCC2 A2
RFIN/ SHDN
B1
MATCH
MATCH
MATCH
B3
RFOUT
MAX2244 MAX2245 MAX2246
PC A1 ANALOG INTERFACE C3 GND C1 GND
CONTROL AMP
POWER DETECTOR
B2 GND
A3 GND
Bluetooth is a trademark of Ericsson Corp. UCSP is a trademark of Maxim Integrated Products, Inc.
HomeRF is a trademark of The HomeRF Working Group. 1
________________________________________________________________ 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.
2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control MAX2244/MAX2245/MAX2246
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 = +85C) 9-Pin UCSP (derate 8.8mW/C above TA = +85C).....700mW Operating Temperature Range ...........................-40C to +85C Junction Temperature .....................................................+150C Storage Temperature Range .............................-65C to +150C Continuous Operating Lifetime............10 years x 0.935(TA - 65C) (for operating temperature 65C < TA < 85C)
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 = -40C to +85C, unless otherwise noted. Typical values are at VCC = 3V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER Supply Voltage VPC = 0.5V, TA = +25C MAX2244 PRFIN = 0 to 4dBm, 2.45GHz VPC = 0.5V, TA = -40C to +85C VPC = 2V, TA = +25C VPC = 2V, TA = -40C to +85C VPC = 0.9V, TA = +25C Supply Current (Note 2) MAX2245 PRFIN = 0 to 4dBm, 2.45GHz VPC = 0.9V, TA = -40C to +85C VPC = 2.2V, TA = +25C VPC = 2.2V, TA = -40C to +85C VPC = 0.5V, TA = +25C MAX2246 VPC = 0.5V, TA = -40C to +85C PRFIN = 0 to 4dBm, VPC = 2V, TA = +25C 2.45GHz VPC = 2V, TA = -40C to +85C Shutdown Supply Current SHDN Input Voltage High SHDN Input Voltage Low SHDN Input Current PC Input Voltage Range PC Input Current Active control range MAX2244/MAX2246 MAX2245 -1 0.5 0.9 -15 -20 SHDN = GND 2.0 0.6 1 2.0 2.5 5 10 42 118 0.5 179 65 172 CONDITIONS MIN 3.0 65 TYP MAX 3.6 83 98 200 205 87 93 195 208 55 61 140 144 10 A V V A V A mA UNITS V
MAX2244/MAX2246, VPC = 0 to 2.5V MAX2245, VPC = 0 to 3V
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2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control
AC ELECTRICAL CHARACTERISTICS
(Typical Application Circuit, VCC = 3V, PRFIN = 0 to 4dBm, fRFIN = 2.45GHz, 50 system, V SHDN 2V, TA = +25C, unless otherwise noted. Typical values are at VCC = 3V, PRFIN = 2dBm, fRFIN = 2.45GHz, TA = +25C, unless otherwise noted.)
PARAMETER Frequency Range (Note 3) Input Power 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) Nonharmonic Spurious Output (Note 2) Power Ramp Turn-On Time (Notes 2, 6) Power Ramp Turn-Off Time (Notes 2, 7) Input VSWR (Note 2) PRFOUT at any level TA = +25C TA = +25C TA = -40C to +85C TA = +25C TA = +25C TA = -40C to +85C TA = +25C TA = +25C TA = -40C to +85C MAX2244/MAX2245 MAX2246 CONDITIONS MIN 2.4 0 0 20.5 20 0 20.5 20 -4.5 19 17 -7 -16 -20 -20 -40 -30 4 4 1.8 1.8 1.5:1 2:1 0.5 20 4 22.0 4 22.0 TYP MAX 2.5 4 7 23.5 24 7 23.5 24 5.5 21 21 -1 -13 -30 dBm dBm dBc dBm dBm s s dBm UNITS GHz dBm
MAX2244/MAX2245/MAX2246
V SHDN 0.6V, PRFIN = 4dBm Frequency offset = 500kHz Frequency offset = 1.5MHz Frequency offset = 2.5MHz All power levels, load VSWR 3:1 MAX2244/MAX2246, VPC steps from 0 to 2V MAX2245/MAX2246, VPC steps from 0 to 2.5V MAX2244, VPC steps from 2V to 0 MAX2245, VPC steps from 2.5V to 0 RS = 50, over full PRFIN range
Note 1: Limits are 100% production tested at TA = +25C. 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.
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2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control MAX2244/MAX2245/MAX2246
Typical Operating Characteristics
(Typical Application Circuit, VCC = 3V, PRFIN = 2dBm, fRFIN = 2.45GHz, SHDN = VCC, TA = +25C, unless otherwise noted.)
MAX2244 OUTPUT POWER vs. POWER CONTROL (VPC)
MAX2244-46 toc01
MAX2244 OUTPUT POWER vs. POWER CONTROL (VPC)
20 VCC = 4V
MAX2244-46 toc02
MAX2244 SUPPLY CURRENT vs. POWER CONTROL (VPC)
MAX2244-46 toc03
200
20 OUTPUT POWER (dBm) TA = +85C
10
10
VCC = 3V
SUPPLY CURRENT (mA)
OUTPUT POWER (dBm)
150
TA = +85C
100 TA = +25C 50 TA = -40C
0 TA = +25C -10 TA = -40C
0
-10 VCC = 5.0V
-20 0 0.5 1.0 1.5 2.0 2.5 VPC (V)
-20 0 0.5 1.0 1.5 2.0 2.5 VPC (V)
0 0 0.5 1.0 VPC (V) 1.5 2.0 2.5
MAX2244 OUTPUT POWER vs. FREQUENCY
MAX2244-46 toc04
MAX2244 OUTPUT POWER vs. INPUT POWER
MAX2244-46 toc05
MAX2244 HARMONIC OUTPUT SPECTRUM
VPC = 2V
MAX2244-46toc06
25 VPC = 2.0V 20 OUTPUT POWER (dBm) VPC = 1.0V 15
25 VPC = 2V 20 OUTPUT POWER (dBm) VPC = 1V 15
0dBm
10dB/div 10 fO VPC = 0.5V 5 2fO 3fO 4fO
5fO
10 VPC = 0.5V 5
0 2.40 2.42 2.44 2.46 2.48 2.50 FREQUENCY (GHz)
0 -15 -10 -5 INPUT POWER (dBm) 0 5 0.1 FREQUENCY (GHz) 13
MAX2244 FSK MODULATED OUTPUT SPECTRUM
VPC = 2V
MAX2244-46 toc07
MAX2244 POWER-ON/OFF CHARACTERISTICS
30 20 OUTPUT POWER (dBm) 10 0 -10 -20 -30 -40 PRFOUT
MAX2244-46 toc08
5 4 3 VSHDN (V) 2 1 0
0dBm
VSHDN
10dB/div
2.45GHz 0.5MHz/div
TIME (2s/div)
4
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2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control
Typical Operating Characteristics (continued)
(Typical Application Circuit, VCC = 3V, PRFIN = 2dBm, fRFIN = 2.45GHz, SHDN = VCC, TA = +25C, unless otherwise noted.)
MAX2245 OUTPUT POWER vs. POWER CONTROL (VPC)
20 OUTPUT POWER (dBm)
MAX2244-46 toc09
MAX2244/MAX2245/MAX2246
MAX2245 OUTPUT POWER vs. POWER CONTROL (VPC)
20 VCC = 4V OUTPUT POWER (dBm) VCC = 5V 10 VCC = 3V
MAX2244-46 toc10
MAX2245 SUPPLY CURRENT vs. POWER CONTROL (VPC)
MAX2244-46 toc11
200 TA = +85C SUPPLY CURRENT (mA) 150
10 TA = +85C
100
TA = +25C TA = -40C
0
0
-10
TA = +25C TA = -40C
-10
50
-20 0 0.5 1.0 1.5 VPC (V) 2.0 2.5 3.0
-20 0 0.5 1.0 1.5 VPC (V) 2.0 2.5 3.0
0 0 0.5 1.0 1.5 VPC (V) 2.0 2.5 3.0
MAX2245 OUTPUT POWER vs. FREQUENCY
MAX2244-46 toc12
MAX2245 OUTPUT POWER vs. INPUT POWER
MAX2244-46 toc13
MAX2245 HARMONIC OUTPUT SPECTRUM
VPC = 2.2V
MAX2244/45 toc14
25 VPC = 2.5V 20 OUTPUT POWER (dBm) VPC = 1.5V 15
25 VPC = 2.5V 20 OUTPUT POWER (dBm) VPC = 1.5V 15
0dBm
10dB/div 10 fO VPC = 1V 5 2fO 3fO 4fO
10 VPC = 1V 5
5fO
0 2.40 2.42 2.44 2.46 2.48 2.50 FREQUENCY (GHz)
0 -15 -10 -5 INPUT POWER (dBm) 0 5 0.1 FREQUENCY (GHz) 13
MAX2245 FSK MODULATED OUTPUT SPECTRUM
MAX2244-46 toc15
SHUTDOWN CURRENT vs. TEMPERATURE
MAX2244-46 toc16
VPC = 2.2V
800
SHUTDOWN CURRENT (nA)
0dBm
600
10dB/div
400
200
0 2.45GHz 0.5MHz/div -40 -20 0 20 40 60 80 TEMPERATURE (C)
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2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control MAX2244/MAX2245/MAX2246
Typical Operating Characteristics (continued)
(Typical Application Circuit, VCC = 3V, PRFIN = 2dBm, fRFIN = 2.45GHz, SHDN = VCC, TA = +25C, unless otherwise noted.)
MAX2246 OUTPUT POWER vs. POWER CONTROL (VPC)
20 OUTPUT POWER (dBm) TA = +85C 10
MAX2244-46 toc017
MAX2246 OUTPUT POWER vs. POWER CONTROL (VPC)
20 OUTPUT POWER (dBm) VCC = 5V 10 VCC = 4V VCC = 3V
MAX2244-46 toc18
MAX2246 SUPPLY CURRENT vs. POWER CONTROL (VPC)
MAX2244-46 toc19
200
SUPPLY CURRENT (mA)
150 TA = +85C 100
0
0
-10
TA = +25C TA = -40C
-10
50 TA = -40C
TA = +25C
-20 0 0.5 1.0 1.5 2.0 2.5 VPC (V)
-20 0 0.5 1.0 1.5 2.0 2.5 VPC (V)
0 0 0.5 1.0 VPC (V) 1.5 2.0 2.5
MAX2246 OUTPUT POWER vs. FREQUENCY
MAX2244-46 toc20
MAX2246 OUTPUT POWER vs. INPUT POWER
MAX2244-46 toc21
MAX2246 HARMONIC OUTPUT SPECTRUM
VPC = 2V
MAX2244-46 toc22
25 VPC = 2V
25
20 OUTPUT POWER (dBm)
20 OUTPUT POWER (dBm) VPC = 2V 15 VPC = 1V
0dBm
15
VPC = 1V
10dB/div fO 2fO 3fO 4fO
10
10
5fO
5 VPC = 0.5V 0 2.40 2.42 2.44 2.46 2.48 2.50 FREQUENCY (GHz)
5 VPC = 0.5V 0 -15 -10 -5 INPUT POWER (dBm) 0 5 0.1 FREQUENCY (GHz) 13
MAX2246 FSK MODULATED OUTPUT SPECTRUM
MAX2244-46 toc23
S11 OF RFIN
1: -20.322dB AT 2.4GHz 2: -13.482dB AT 2.5GHz 2
MAX2244-46 toc24
VPC = 2V
0 -5 S11 MAGNITUDE (dB) -10 -15 -20 1 -25 -30
0dBm
10dB/div
2.45GHz 0.5MHz/div
2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 FREQUENCY (GHz)
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2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control
Pin Description
PIN A1 A2 A3, B2, C1, C3 B1 B3 C2 NAME PC VCC2 GND RFIN/SHDN RFOUT VCC1 DESCRIPTION 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. DC Supply-Voltage Connection for the 2nd Stage Ground Connection. Connect to the PC board ground plane. Provide inductance connection as low as is practical to the ground plane. RF Input and Digital Shutdown Control Input. RF path internally DC-blocked and matched to 50. Digital shutdown path is connected to the bias circuitry through a resistor. 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
MAX2244/MAX2245/MAX2246
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 50, 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 10F 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.
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2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control MAX2244/MAX2245/MAX2246
VCC
C1 10F
C2 10nF
TRANSCEIVER IC T4 DAC R2 2.5k PC A1 RFIN/ SHDN RFIN C5 10pF SHDN R2 1k B1 VCC2 A2
C4 27pF
C3 1nF
T1 GND A3 C10 C11 1nF
GND B2
RFOUT B3
C6
T2 RFOUT C7
GND C1
VCC1 C2
GND C3
MAX2244 MAX2245 MAX2246
T3
C8
C9 1nF
Figure 1. MAX2244/MAX2245/MAX2246 Typical Application Circuit
Table 1. Typical Application Circuit Component Values
COMPONENT C6 C7 C8 C10 T1 T2 T3 T4 MAX2244 10pF 1.2pF 5pF 100pF 50, 17.6 50, 50 50, 5.3 50, 5.3 MAX2245 5.6pF 1.2pF 5pF 100pF 50, 18 50, 53 50, 5.3 50, 5.9 MAX2246 10pF 1.3pF 27pF 27pF 50, 25 50, 50 50, 5.3 50, 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 (~10), 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
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 50, making it simple to interface the PAs to a 50 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 1k 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
MATCHING IMPEDANCE FOR RFOUT PIN
SMITH CHART
MAX2244: 6.26 + j13.56 AT 2.45GHz MAX2245: 6.35 + j13.25 AT 2.45GHz MAX2246: 5.50 + j13.50 AT 2.45GHz
Figure 2. Impedance of Matching Network at RFOUT Pin
Table 2. Matching Network Impedance
MAX2244 FREQUENCY REAL IMAG GHz () () 2.40 2.45 2.50 6.47 6.26 6.06 13.2 13.5 13.9 MAX2245 MAX2246 REAL IMAG REAL IMAG () () () () 6.61 6.35 6.11 12.94 13.25 13.59 5.73 5.50 5.27 13.01 13.50 14.02
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 6 to 50 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 50 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 50 transmission line (T1); however, chip inductors can be used instead. The typical application circuit terminates the transmission line with a capacitor (C6).
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.
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2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control MAX2244/MAX2245/MAX2246
MAX2244 TYPICAL OUTPUT POWER POUT vs. VPC
25
20
15
10
POUT (dBm)
5
0
-5
-10
-15
-20 0 0.50 1.00 1.50 2.00 2.50
VPC (V)
VPC (V) 0 0.30 0.32 0.36 0.37 0.38 0.39 0.40 0.41
POUT (dBm) -9.45 -9.45 -9.45 -9.50 -9.55 -10.79 -15.60 -8.65 -5.41
VPC (V) 0.42 0.43 0.44 0.45 0.46 0.47 0.48 0.50 0.52
POUT (dBm) -3.24 -1.85 -0.64 0.43 1.24 1.97 2.62 3.79 4.75
VPC (V) 0.54 0.56 0.58 0.60 0.65 0.70 0.75 0.80 0.85
POUT (dBm) 5.59 6.35 7.04 7.67 9.05 10.22 11.26 12.19 13.01
VPC (V) 0.90 0.95 1.00 1.10 1.20 1.30 1.40 1.50 1.60
POUT (dBm) 13.76 14.45 15.10 16.25 17.26 18.16 18.95 19.65 20.26
VPC (V) 1.70 1.80 1.90 2.00 2.10 2.20 2.30 2.40 2.50
POUT (dBm) 20.79 21.24 21.63 21.91 22.07 22.08 22.09 22.10 22.11
Figure 3a. MAX2244 Typical Output Power vs. Power-Control Voltage
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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
10
POUT (dBm)
5
0
-5
-10
-15
-20 0 0.50 1.00 1.50 2.00 2.50
VPC (V)
VPC (V) 0 0.82 0.83 0.84 0.85 0.86 0.87 0.88 0.89
POUT (dBm) -8.00 -8.00 -8.14 -8.46 -17.51 -8.00 -4.13 -1.90 -0.35
VPC (V) 0.90 0.91 0.92 0.93 0.94 0.95 0.96 0.97 0.98
POUT (dBm) 0.91 1.91 2.78 3.50 4.20 4.83 5.39 5.93 6.44
VPC (V) 0.99 1.00 1.10 1.20 1.30 1.40 1.50 1.60 1.70
POUT (dBm) 6.90 7.33 10.64 12.99 14.84 16.33 17.61 18.70 19.59
VPC (V) 1.80 1.90 2.00 2.10 2.20 2.30 2.40 2.50 --
POUT (dBm) 20.27 20.79 21.22 21.59 21.91 22.15 22.20 22.20 --
Figure 3b. MAX2245 Typical Output Power vs. Power-Control Voltage
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11
2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control MAX2244/MAX2245/MAX2246
MAX2246 TYPICAL OUTPUT POWER POUT vs. VPC
25
20
15
10
POUT (dBm)
5
0
-5
-10
-15
-20 0 0.50 1.00 1.50 2.00 2.50
VPC (V)
POUT (dBm) -17.80 -17.80 -17.80 -17.78 -17.65 -17.60 -17.53 -17.44 -17.49 POUT (dBm) -16.00 -11.80 -8.74 -6.65 -5.02 -3.67 -2.65 -1.78 -1.02 POUT (dBm) -0.31 0.30 2.75 4.75 6.03 7.26 8.35 9.28 10.89 POUT (dBm) 12.26 13.43 14.60 15.39 16.21 16.97 17.67 18.31 18.93 POUT (dBm) 19.48 19.95 20.33 20.66 20.81 20.82 20.82 -- --
VPC (V) 0 0.10 0.20 0.30 0.35 0.36 0.37 0.38 0.39
VPC (V) 0.40 0.41 0.42 0.43 0.44 0.45 0.46 0.47 0.48
VPC (V) 0.49 0.50 0.51 0.52 0.53 0.54 0.55 0.56 0.57
VPC (V) 1.00 1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80
VPC (V) 1.90 2.00 2.10 2.20 2.30 2.40 2.50 -- --
Figure 3c. MAX2246 Typical Output Power vs. Power-Control Voltage
12
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2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control
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. 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 10F 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 50 traces are used as part of the matching. See the Output Matching section for component information. The 50 traces can be bent, but be aware of how the characteristics of the transmission line change, and compensate for them accordingly. Use a 50 line to directly connect to the input. Place one pad of the 1k resistor for the SHDN signal directly on the 50 line or as close to the line as possible. Any trace connected to the 50 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 (19.7 mil) and a bump diameter of 0.3mm (~12 mil). Therefore, lay out the solder pad spacing on 0.5mm (19.7 mil) centers. Use a pad size of 0.25mm (~10 mil) and a solder mask opening of 0.33mm (13 mil). Round or square pads are permissible. Refer to the Maxim document, Wafer Level Ultra-Chipscale Packaging, for detailed information on UCSP layout and handling. AAA XXX
Marking Information
Pin 1 ID AAA: Product ID Code XXX: Lot Code
MAX2244/MAX2245/MAX2246
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. Users should also be aware that, as with any interconnect system there are electromigration-based current limits that, in this case, apply to the maximum allowable current in the bumps. Reliability is a function of this current, the duty cycle, lifetime, and bump temperature. See the Absolute Maximum Ratings section for any specific limitations, listed under Continuous Operating Lifetime.
Chip Information
TRANSISTOR COUNT: 727 PROCESS: Bipolar
Pin Configuration
TOP VIEW (BUMPS AT THE BOTTOM) 1 PC A A1 RFIN/ SHDN B B1 GND C C1 2 VCC2 A2 3 GND A3
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.
GND B2 VCC1 C2 UCSP
RFOUT B3 GND C3
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2.5GHz, 22dBm/20dBm Power Amplifiers with Analog Closed-Loop Power Control MAX2244/MAX2245/MAX2246
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.)
9LUCSP, 3x3.EPS
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 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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