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19-2494; Rev 2; 8/03
KIT ATION EVALU LE B AVAILA
5GHz Linear Power Amplifiers
General Description Features
5GHz to 6GHz Operating Frequency Range High Linear Output Power +15dBm at 5.25GHz (MAX2840) +18dBm at 5.25GHz (MAX2841) 22dB Power Gain On-Chip Detector With 15dB Dynamic Range and 1.0dB Detector Accuracy Simple Input and Output Matching +2.7V to +3.6V Single Supply Shutdown Mode With Less than 10A Current 2mm 1.5mm Chip-Scale Package
MAX2840/MAX2841
The MAX2840/MAX2841 low-cost linear power amplifiers (PAs) operate in the 5GHz to 6GHz band. The PAs are designed for high gain and high linearity, which makes them ideal for use in IEEE 802.11a OFDM systems. The MAX2840 delivers +15dBm output power, and the MAX2841 delivers +18dBm output power. The devices integrate a power detector that provides over 15dB dynamic range and 1.0dB accuracy. With the detector circuit built in, an automatic level control (ALC) function can be easily implemented. The PAs also feature an external bias control function. The idle current can be adjusted through an external DAC to improve efficiency at reduced output powers while maintaining sufficient ACPR and EVM performance. As a result, the highest possible efficiency is maintained at all power levels. The MAX2840/MAX2841 operate over a single +2.7V to +3.6V power-supply range. An on-chip shutdown feature reduces operating current to less than 10A, eliminating the need for an external supply switch. The MAX2840/MAX2841 are packaged in a 2mm 1.5mm chip-scale package (UCSPTM), which significantly minimizes parasitic effects and reduces the required board area.
Ordering Information
PART MAX2840EBC-T MAX2841EBC-T TEMP RANGE -40C to +85C -40C to +85C PINPACKAGE 3 4 UCSP 3 4 UCSP TOP MARK AAT AAU
Typical Operating Circuit appears at end of data sheet.
Applications
IEEE 802.11a OFDM WLAN HiperLAN2 WLAN 5GHz Cordless Phones
SHDN A1 BIAS CIRCUIT BIAS C1
Pin Configuration
Functional Diagram
SHDN P_DET
GND A2 BIAS BIAS CIRCUIT DETECTOR
RF_IN B2
MAX2840 MAX2841 GND C2
VCC
MAX2840 MAX2841
VCC A3
P_DET C3
RF_IN
RF_OUT DET
A4 GND GND GND GND GND
B4 RF_OUT
C4 GND
UCSP is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ 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.
5GHz Linear Power Amplifiers MAX2840/MAX2841
ABSOLUTE MAXIMUM RATINGS
VCC to GND ...........................................................-0.3V to +4.2V SHDN, BIAS, P_DET, RF_OUT to GND ......-0.3V to (VCC + 0.3V) RF_IN to GND........................................................-0.3V to +0.9V Input Power ................................................................... +10dBm Max VSWR Without Damage .................................................10:1 Max VSWR for Stable Operation .............................................5:1 Continuous Operating Lifetime.....................10yrs 0.93(TA - 60C) (for operating temperature 60C < TA < 85C) Continuous Power Dissipation (TA = +85C) 3 4 UCSP (derate 80mW/C above +85C) .................. 1.6W Operating Temperature Range ...........................-40C to +85C Thermal Resistance .........................................................25C/W Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +125C Soldering Temperature (10s) ...........................................+260C
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 = +2.7V to +3.6V, GND = 0V, SHDN = VCC, VDAC = 1.6V (MAX2840), VDAC = 1.9V (MAX2841), TA = -40C to +85C. Typical values are measured at VCC = +3.3V, fRF = 5.25GHz, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER Supply Voltage POUT = 15dBm, VCC = 3.3V, MAX2840 (Notes 2, 3) POUT = 18dBm, VCC = 3.3V, MAX2841 (Notes 2, 3) Supply Current No RF signal, RF input and output terminated with 50 SHDN = 0V, no RF signal Digital Input Voltage High Digital Input Voltage Low Digital Input Current High Digital Input Current Low -1 2 0.8 5 MAX2840 MAX2841 CONDITIONS MIN 2.7 155 260 120 165 0.5 10 A V V A A TYP MAX 3.6 190 310 mA UNITS V
AC ELECTRICAL CHARACTERISTICS
(MAX2840/MAX2841 EV kits, VCC = +2.7V to +3.6V, GND = 0V, SHDN = VCC, VDAC = 1.6V (MAX2840), VDAC = 1.9V (MAX2841), TA = +25C. Typical values are measured at VCC = +3.3V, fRF = 5.25GHz, unless otherwise noted.) (Note 3)
PARAMETER RF Frequency Range Power Gain (Note 5) Power Gain (Note 4) POUT = 15dBm (MAX2840) POUT = 18dBm (MAX2841) TA = +85C, VCC = 3.3V (Note 5) ACPR: -23dBc at 11MHz offset, -31dBc at 20MHz offset, -43dBc at 30MHz offset over 100kHz BW; OFDM, 64-QAM signal (Notes 6, 7) POUT = 15dBm (MAX2840) POUT = 18dBm (MAX2841) POUT = 15dBm (MAX2840) POUT = 18dBm (MAX2841) MAX2840 MAX2841 19.5 15 dBm 18 3.9 3.5 -45 %RMS dBc CONDITIONS MIN 5.15 22.8 22.5 TYP MAX 5.35 UNITS GHz dB dB
Output Power
Error Vector Magnitude (Note 7) Harmonic Output (2f, 3f)
2
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5GHz Linear Power Amplifiers
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2840/MAX2841 EV kits, VCC = +2.7V to +3.6V, GND = 0V, SHDN = VCC, VDAC = 1.6V (MAX2840), VDAC = 1.9V (MAX2841), TA = +25C. Typical values are measured at VCC = +3.3V, fRF = 5.25GHz, unless otherwise noted.) (Note 3)
PARAMETER Input VSWR Output VSWR Nonharmonic Spurious Output Power Ramp Turn-On Time Power Ramp Turn-Off Time RF Output Detector Response Time SHDN from low to high (Note 8) SHDN from high to low (Note 8) External capacitor, C = 10pF POUT = 15dBm (MAX2840) POUT = 18dBm (MAX2841) RF Output Detector Voltage Range Load >100k (Note 7) POUT = 12dBm (MAX2840) POUT = 15dBm (MAX2841) POUT = 5dBm (MAX2840) POUT = 5dBm (MAX2841) RF Output Detector Accuracy RF Output Detector Slope When output detector voltage = 1.2V At maximum output power 1 1 0.5 1.1 1.2 1 1 0.7 0.7 1 6 dB dB/V V CONDITIONS MIN TYP 1.8:1 1.9:1 -60 1.5 1.5 1.5 dBc s s s MAX UNITS
MAX2840/MAX2841
Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8:
Specifications over temperature range are guaranteed by design. Production tests are performed at TA = +85C. 5.25GHz 64-QAM modulated OFDM signal is applied at RF input port. Min and max values are guaranteed by design and characterization. Operation outside of this frequency range is possible but not guaranteed. Specifications are corrected for board losses on the EV kits (0.3dB at the input, 0.3dB at the output). RF input signal is following IEEE 802.11a standards. Specifications are corrected for board losses on the EV kits (0.3dB at the output). The total turn-on/settling time required for PA output power is within 0.5dB range of the final value.
Typical Operating Characteristics
(MAX2840/MAX2841 EV kits, VCC = +2.7V to +3.6V, GND = 0V, SHDN = VCC, VDAC = 1.6V (MAX2840), VDAC = 1.9V (MAX2841), TA = +25C. Typical values are measured at VCC = +3.3V, fRF = 5.25GHz, unless otherwise noted.) (Note 2)
MAX2840 SUPPLY CURRENT vs. SUPPLY VOLTAGE
PIN = -8.9dBm 160
MAX2840/41 toc01
MAX2840 SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
MAX2840/41 toc02
180
0.30 0.25 SHUTDOWN CURRENT (A) 0.20 0.15 TA = +25C 0.10 0.05 TA = +85C
SUPPLY CURRENT (mA)
140
120
TA = -40C 2.7 3.0 3.3 3.6
100 2.7 3.0 3.3 3.6 SUPPLY VOLTAGE (V)
0 SUPPLY VOLTAGE (V)
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3
5GHz Linear Power Amplifiers MAX2840/MAX2841
Typical Operating Characteristics (continued)
(MAX2840/MAX2841 EV kits, VCC = +2.7V to +3.6V, GND = 0V, SHDN = VCC, VDAC = 1.6V (MAX2840), VDAC = 1.9V (MAX2841), TA = +25C. Typical values are measured at VCC = +3.3V, fRF = 5.25GHz, unless otherwise noted.) (Note 2)
MAX2840 SUPPLY CURRENT vs. OUTPUT POWER
MAX2840/41 toc03
MAX2840 POWER-ADDED EFFICIENCY (PAE) vs. OUTPUT POWER
16 2.7V 14 12 PAE (%) 10 8 6 4 3.0V
MAX2840/41 toc04
MAX2840 POWER DETECTOR OUTPUT vs. OUTPUT POWER
MAX2840/41 toc05
220 200 SUPPLY CURRENT (mA) 180 160 140 120
18
1.2 POWER DETECTOR OUTPUT (V) 1.1 1.0 0.9 0.8 0.7 0.6
2 100 0 4 8 12 16 20 OUTPUT POWER (dBm) 0 0 4 8 12
3.6V
16
20
0
4
8
12
16
OUTPUT POWER (dBm)
OUTPUT POWER (dBm)
MAX2840 INPUT AND OUTPUT RETURN LOSS vs. FREQUENCY
MAX2840/41 toc06
MAX2840 GAIN vs. FREQUENCY
MAX2840/41 toc07
MAX2840 ACPR SPECTRUM
PO = +15dBm
MAX2840/41 toc08
0 INPUT AND OUTPUT RETURN LOSS (dB)
30 PIN = -8.9dBm 25 GAIN (dB)
-4
-8
S11
20
-12
S22 15
-16
-20 5150
10 5200 5250 FREQUENCY (MHz) 5300 5350 5150 5200 5250 FREQUENCY (MHz) 5300 5350 SPAN: 100MHz CENTER: 5.25GHz
OUTPUT POWER, 10dB/div 280 PIN = -4.8dBm 260
MAX2840 EVM vs. OUTPUT POWER
MAX2840/41 toc09
MAX2840 EVM vs. FREQUENCY
PIN = -8.9dBm 5 EVM (%) VCC = 3.0V 4 VCC = 3.3V
MAX2840/41 toc10
MAX2841 SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX2840/41 toc011
6 PIN = -8.9dBm 5 EVM (%)
6
SUPPLY CURRENT (mA)
4 VCC = 3.0V 3 VCC = 3.3V
240
3
220
2 12 13 14 15 16 OUTPUT POWER (dBm)
2 5150 5200 5250 FREQUENCY (MHz) 5300 5350
200 2.7 3.0 3.3 3.6 SUPPLY VOLTAGE (V)
4
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5GHz Linear Power Amplifiers MAX2840/MAX2841
Typical Operating Characteristics (continued)
(MAX2840/MAX2841 EV kits, VCC = +2.7V to +3.6V, GND = 0V, SHDN = VCC, VDAC = 1.6V (MAX2840), VDAC = 1.9V (MAX2841), TA = +25C. Typical values are measured at VCC = +3.3V, fRF = 5.25GHz, unless otherwise noted.) (Note 2)
MAX2841 SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
MAX2840/41 toc12
MAX2841 SUPPLY CURRENT vs. OUTPUT POWER
MAX2840/41 toc13
MAX2841 POWER-ADDED EFFICIENCY (PAE) vs. OUTPUT POWER
16 14 12 PAE (%) 2.7V
MAX2840/41 toc14
0.30 0.25 SHUTDOWN CURRENT (A) 0.20 0.15 TA = +25C 0.10 0.05 0 2.7 3.0 3.3 TA = +85C
400 350 SUPPLY CURRENT (mA) 300 TA = +25C 250 200 150 100 TA = -40C TA = +85C
18
10 8 6 4 2 0 3.6V 3.0V
TA = -40C 3.6
0
4
8
12
16
20
24
0
5
10
15
20
25
SUPPLY VOLTAGE (V)
OUTPUT POWER (dBm)
OUTPUT POWER (dBm)
MAX2841 POWER DETECTOR OUTPUT vs. OUTPUT POWER
MAX2840/41 toc15
MAX2841 INPUT AND OUTPUT RETURN LOSS vs. FREQUENCY
MAX2840/41 toc16
MAX2841 GAIN vs. FREQUENCY
PIN = -4.8dBm 25 GAIN (dB)
MAX2840/41 toc17
2.0 POWER DETECTOR OUTPUT (V) 1.8 1.6 1.4 1.2 1.0 TA = -40C 0.8 0.6 0 5 10 15 20 TA = +25C TA = +85C
0 INPUT AND OUTPUT RETURN LOSS (dB)
30
-4
-8
S22
20
-12 S11 -16
15
25
-20 5150
10 5200 5250 FREQUENCY (MHz) 5300 5350 5150 5200 5250 FREQUENCY (MHz) 5300 5350
OUTPUT POWER (dBm)
MAX2841 ACPR SPECTRUM
MAX2840/41 toc18
MAX2841 EVM vs. OUTPUT POWER
MAX2840/41 toc19
MAX2841 EVM vs. FREQUENCY
PIN = -4.8dBm 5 EVM (%)
MAX2840/41 toc20
6 PIN = -4.8dBm 5 EVM (%)
6
POUT = +18dBm OUTPUT POWER, 10dB/div
4 VCC = 3.0V
4
VCC = 3.0V VCC = 3.3V
3
VCC = 3.3V
3
2 CENTER: 5.25GHz SPAN: 100MHz 13 14 15 16 17 18 19 OUTPUT POWER (dBm)
2 5150 5200 5250 FREQUENCY (MHz) 5300 5350
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5
5GHz Linear Power Amplifiers MAX2840/MAX2841
Pin Description
PIN A1 A2, A4, C2, C4 A3 B2 B4 C1 C3 NAME SHDN GND VCC RF_IN RF_OUT BIAS P_DET DESCRIPTION Shutdown Input. Drive logic low to place the PA in shutdown mode; drive logic high for normal operation. Ground. Requires a good connection to the circuit board ground plane with multiple vias for lowest possible inductance and lowest thermal resistance. DC Supply Voltage. Requires external RF bypass capacitor to ground. Power Amplifier Input. Requires external DC-blocking capacitor. Power Amplifier Output. Requires external DC-blocking capacitor and pullup inductor. Bias Control. Connect two external resistors and DAC block to adjust the bias current. Power Detector Output. This output is a DC voltage indicating the PA output power.
Detailed Description
The MAX2840/MAX2841 linear power amplifiers (PAs) are intended for 5GHz to 6GHz band applications. The PAs are fully characterized in the 5.15GHz to 5.35GHz band. The PAs consist of two driver stages and an output stage. The ICs also feature an integrated power detector and power shutdown mode.
[Equation 2] IMAX = PART 1.2 / 2000 + (R1 R2) / (R1 + R2); (ICC = IMAX = max value, VDAC = 0) [Equation 3] IDAC = (VDAC - 0.82) / R1 [Equation 4] IMID = PART 1.2 / (2000 + R2); (VDAC = floating) [Equation 5] ICC = PART IBIAS where: VMAX IMAX IMID VDAC
Dynamic Power Control
The MAX2840/MAX2841 are designed to provide optimum power-added efficiency (PAE) in both high- and low-power applications. For a +3.3V supply at high-output power level, the output power is typically +18dBm (MAX2841) with an idle current of 165mA, or +15dBm (MAX2840) with an idle current of 120mA. At low-output power levels, the DC current can be reduced by an external DAC to improve PAE while maintaining sufficient ACPR performance. This is achieved by using external resistors connected to the BIAS pin to set the bias currents of the driver and output stages. See the Typical Application Circuit for resistor values. Typically, a DAC voltage of 1.9V gives a 260mA bias current for the MAX2841, a DAC voltage of 1.6V gives a 155mA bias current for the MAX2840. Increasing the DAC voltage decreases the idle current. Similarly, decreasing the DAC voltage increases the idle current. Users can set the desired idle current using only two off-chip 1% resistors: a shunt resistor (R2) from BIAS to ground and a series resistor (R1) to the DAC voltage, as shown in the Typical Application Circuit. Resistor values R1 and R2 are determined as follows: [Equation 1] VMAX = 1.2 (R1 + R2) / R2; (ICC = 0, VDAC = VMAX)
= maximum DAC voltage = maximum idle current = idle current with VDAC = floating = DAC voltage
IDAC = DAC current PART = 1000 for MAX2840, 1600 for MAX2841 If no DAC is used and a constant idle current is desired, use Equation 4 to determine the resistor values for a given total bias current. Only R2 is required. For a DAC capable of sourcing and sinking currents, the full voltage range of the DAC (typically from 0 to +3V) can be used. By substituting the desired values of VMAX and IMAX into Equations 1 and 2, R1 and R2 can be easily calculated. For a DAC capable of sourcing current only, use Equation 4 to determine the value of resistor R2 for the desired maximum current. Use Equation 1 to determine the value of resistor R1 for the desired minimum current.
6
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5GHz Linear Power Amplifiers
For a DAC capable of sinking current only, set resistors R1 and R2 to 0 and connect the DAC directly to the BIAS pin. Use Equation 5 to determine the DAC current required for a given ICC.
Ground Vias
Placement and type of ground vias are important to achieve optimum gain and output power and ACPR performance. Each ground pin requires its own via on pad (via diameter = 8 mils) placed under the device pin to reduce ground inductance and feedback between stages. Use the MAX2840/MAX2841 EV kit PC board layouts as a guide.
MAX2840/MAX2841
Shutdown Mode
Apply logic low to SHDN (pin A1) to put the MAX2840/ MAX2841 in shutdown mode. In this mode, all gain stages are disabled and supply current drops to less than 10A. Note that the shutdown current is lowest when VSHDN = 0.
Layout and Thermal Management Issues
The MAX2840/MAX2841 EV kits serve as a layout guide. Use controlled-impedance lines on all high-frequency inputs and outputs. The GND pins also serve as heatsinks. Connect all GND pins directly to the topside RF ground. On boards where the ground plane is not on the component side, connect all GND pins to the ground plane with plated multiple through holes close to the package. PC board traces connecting the GND pins also serve as heatsinks. Make sure the traces are sufficiently wide.
Power Detector
The power detector generates a voltage proportional to the output power. It is fully temperature compensated and allows the user to set the bandwidth with an external capacitor. For maximum bandwidth, connect a 100k resistor from P_DET to GND and do not use any external capacitors.
Applications Information
Supply Bypassing
VCC provides bias to the first- and second-stage amplifiers. See the Typical Application Circuit for the lumped and discrete component values used on the MAX2840/MAX2841 EV kits for optimum RF bypassing. In addition to RF bypass capacitors on each bias line, a global bypass capacitor of 10F is necessary to filter any noise on the supply line. Route separate VCC bias paths from the global bypass capacitor (star topology) to avoid coupling between PA stages. Use the MAX2840/MAX2841 EV kits PC board layout as a guide.
UCSP Reliability
The chip-scale package (UCSP) is a unique package that greatly reduces board space. UCSP reliability is integrally linked to the user's assembly methods, circuit board material, and usage environment. The user should closely review these areas when considering using a UCSP. This form factor might not perform equally to a packaged product through traditional mechanical reliability tests. Performance through operating life test and moisture resistance remains uncompromised, as it is 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, which can be found on Maxim's website, www.maxim-ic.com. Users should be aware that, as with any interconnect system, there are electromigration-based current limits, which 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 of the data sheet for any specific limitation, listed under "Continuous Operating Lifetime."
External Matching
The RFIN port requires a matching network. The RFIN port impedance is 11 + j14 at 5.25GHz. See the Typical Application Circuit for recommended component values. The RFOUT port is an open-collector output that must be pulled to VCC through a 5.6nH RF choke for proper biasing. Two shunt capacitors to ground are required at the supply side of the inductor. In addition, a matching network is required for optimum gain, efficiency, ACPR, and output power. The load impedance seen at the RFOUT port of the MAX2840/ MAX2841 on the EV kits is approximately 13 + j5. This should serve as a good starting point for the layout. However, optimum performance is layout dependent and some component optimization may be required. See the Typical Application Circuit for the lumped and discrete component values used on the MAX2840/ MAX2841 EV kits to achieve this impedance.
Chip Information
TRANSISTOR COUNT: 1263
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5GHz Linear Power Amplifiers MAX2840/MAX2841
Typical Operating Circuit
10pF SHDN
100k P_DET
DAC
R1 10k R2 5k BIAS
MAX2840 MAX2841 BIAS CIRCUIT DECTECTOR 1000pF VCC 5.6nH 3pF
1000pF
10pF
VCC
6.8pF RF_IN 1.2pF
T1*
T2*
5pF RF_OUT C = 1pF (MAX2841) C = 0.6pF (MAX2840)
GND *T1 = 100 MILS, T2 = 70 MILS (MAX2840) T1 = 80 MILS, T2 = 60 MILS (MAX2841) **BOARD MATERIAL: FR4, DIELECTRIC THICKNESS: 6 MILS
GND
GND
GND
8
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5GHz Linear Power Amplifiers
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.)
12L, UCSP 4x3.EPS
MAX2840/MAX2841
PACKAGE OUTLINE, 4x3 UCSP 21-0104 F
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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