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.