RF2138 2 3V GSM POWER AMPLIFIER Typical Applications • 3V GSM Cellular Handsets • Portable Battery-Powered Equipment • 3V Dual-Band/Triple-Band Handsets • GPRS Compatible 2 POWER AMPLIFIERS • Commercial and Consumer Systems Product Description Optimum Technology Matching® Applied ü Si BJT GaAs HBT GaAs MESFET SiGe HBT Si CMOS NC VCC2 VCC2 NC 2F0 15 14 13 2 12 RF OUT 3 11 RF OUT 4 10 RF OUT 7 8 Functional Block Diagram Rev A9 011031 1.50 1.20 0.38 0.40 sq. R F2 17 3 1 1.50 sq. 2.00 4.20 sq. 3.95 ALL SOLDER PAD TOLERANCES P0.05mm 0.28 0.80 0.13 Package Style: MP16K01A Features • Single 2.7V to 4.8V Supply Voltage • +36dBm Output Power at 3.5V • 32dB Gain with Analog Gain Control • 58% Efficiency • 800MHz to 950MHz Operation • Supports GSM and E-GSM 9 NC 6 VCC VCC1 5 APC2 S ee GND1 16 U pg r RF IN 1 APC1 GND2 ad ed P Si Bi-CMOS 3.50 3.35 sq. ro du ct The RF2138 is a high power, high efficiency power amplifier module offering high performance in GSM or GPRS applications. The device is manufactured on an advanced GaAs HBT process, and has been designed for use as the final RF amplifier in GSM hand held-digital cellular equipment and other applications in the 800MHz to 950MHz band. On-board power control provides over 70dB of control range with an analog voltage input, and provides power down with a logic “low” for standby operation. The device is self-contained with 50Ω input and the output can be easily matched to obtain optimum power and efficiency characteristics. The RF2138 can be used together with the RF2140 for dual-band operation. The device is packaged in an ultra-small ceramic package, minimizing the required board space. Ordering Information RF2138 RF2138 PCBA 3V GSM Power Amplifier Fully Assembled Evaluation Board RF Micro Devices, Inc. 7628 Thorndike Road Greensboro, NC 27409, USA Tel (336) 664 1233 Fax (336) 664 0454 http://www.rfmd.com 2-119 RF2138 Parameter Rating Unit -0.5 to +6.0 -0.5 to +3.0 2400 +13 50 10:1 -40 to +85 -55 to +150 VDC V mA dBm % °C °C Specification Min. Typ. Max. Caution! ESD sensitive device. RF Micro Devices believes the furnished information is correct and accurate at the time of this printing. However, RF Micro Devices reserves the right to make changes to its products without notice. RF Micro Devices does not assume responsibility for the use of the described product(s). Unit Overall +4 58 58 12 5 +6 ad ed Forward Isolation -45 U pg r Second Harmonic Third Harmonic Fourth Harmonic Fifth Harmonic Sixth Harmonic All Non-Harmonic Spurious Input Impedance Optimum Source Impedance Input VSWR Output Load VSWR Output Load Impedance 2-120 +8 -72 -81 dBm -40 -30 -38 -43 -55 -50 -40 -36 -30 dBm dBm dBc dBc dBc dBc dBc dBm dBm Ω Ω +34.0 P Input Power for Max Output Output Noise Power MHz MHz dBm dBm dBm dBm dBm % % % % dBm dBm -50 -65 -65 -65 -65 50 40+j10 2.5:1 4:1 10:1 1.5-j1.7 Condition Temp=25 °C, VCC =3.5V, VAPC1,2 =2.6V, PIN =+6dBm, Freq=880MHz to 915MHz, 25% Duty Cycle, pulse width=1154µs See evaluation board schematic. Temp=25 °C, VCC =3.5V, VAPC1,2 =2.6V Temp=+25 °C, VCC =3.2V, VAPC1,2 =2.6V Temp=+85 °C, VCC =3.2V, VAPC1,2 =2.6V Temp=25 °C, VCC =2.7V, VAPC1,2 =2.6V Temp=+85 °C, VCC =2.7V, VAPC1,2 =2.6V At POUT,MAX, VCC =3.2V At POUT,MAX, VCC =3.0V POUT =+20dBm POUT =+10dBm R F2 17 Total Efficiency +35.0 +34.1 +34.0 +33.0 +32.5 50 880 to 915 800 to 950 +36 +35.2 ro du ct Operating Frequency Range Usable Frequency Range Maximum Output Power S ee POWER AMPLIFIERS 2 Supply Voltage Power Control Voltage (VAPC1,2) DC Supply Current Input RF Power Duty Cycle at Max Power Output Load VSWR Operating Case Temperature Storage Temperature 3 Absolute Maximum Ratings Parameter Ω RBW=100kHz, 925MHz to 935MHz, POUT,MIN <POUT <POUT,MAX, PIN,MIN <PIN <PIN,MAX, VCC =3.0V to 5.0V RBW=100kHz, 935MHz to 960MHz, POUT,MIN <POUT <POUT,MAX, PIN,MIN <PIN <PIN,MAX, VCC =3.0V to 5.0V VAPC1,2 =0.2V, PIN =+6dBm VAPC1,2 =0.2V, PIN =+10dBm POUT =POUT,MAX POUT =POUT,MAX POUT =POUT,MAX POUT =POUT,MAX POUT =POUT,MAX <1GHz >1GHz For best noise performance POUT,MAX-5dB<POUT <POUT,MAX POUT <POUT,MAX-5dB Spurious<-36dBm, VAPC1,2 =0.2V to 2.6V, RBW=100kHz Load Impedance presented at RF OUT pad Rev A9 011031 RF2138 Specification Min. Typ. Max. Parameter Unit Condition V Maximum POUT, Voltage supplied to the input Minimum POUT, Voltage supplied to the input VAPC1,2 =0.2V to 2.6V POUT =-10dBm to +35dBm DC to 2MHz VAPC1,2 =2.6V VAPC1,2 =0V VAPC1,2 =0 to 2.6V Power Control VAPC1 VAPC2 2.6 Power Control “OFF” Power Control Range Gain Control Slope APC Input Capacitance APC Input Current 0.2 75 5 0.5 100 4.5 Turn On/Off Time 150 10 5 10 100 V dB dB/V pF mA µA ns 4.8 5.5 V V V 375 10 10 A mA µA µA Power Supply Power Supply Current 2 200 1 1 S ee U pg r ad ed P ro du ct 50 Specifications Nominal operating limits, POUT <+35dBm With maximum output load VSWR 6:1, POUT <+35dBm DC Current at POUT,MAX Idle Current, PIN <-30dBm PIN <-30dBm, VAPC1,2 =0.2V PIN <-30dBm, VAPC1,2 =0.2V, Temp=+85 °C 3 3.5 2.7 R F2 17 Power Supply Voltage Rev A9 011031 2-121 2 POWER AMPLIFIERS Power Control “ON” RF2138 Function NC 2 GND2 3 RF IN Description Interface Schematic Not connected. Connect this pin to the ground plane for compatibility with future packages. Ground connection for the driver stage. To minimize the noise power at See pin 15. the output, it is recommended to connect this pin with a trace of about 40mil to the ground plane. This will slightly reduce the small signal gain, and lower the noise power. It is important for stability that this pin have it’s own vias to the ground plane, minimizing common inductance. RF Input. This is a 50Ω input, but the actual impedance depends on the interstage matching network connected to pin 5. An external DC blocking capacitor is required if this port is connected to a DC path to ground RF IN or a DC voltage. VCC1 From Bias GND1 Stages 5 VCC1 6 APC1 Ground connection for the pre-amplifier stage. Keep traces physically See pin 3. short and connect immediately to the ground plane for best performance. It is important for stability that this pin has it’s own vias to the groundplane, to minimize any common inductance. Power supply for the pre-amplifier stage and interstage matching. This See pin 3. pin forms the shunt inductance needed for proper tuning of the interstage match. Refer to the application schematic for proper configuration. Note that position and value of the components are important. Power Control for the driver stage and pre-amplifier. When this pin is APC "low," all circuits are shut off. A "low" is typically 0.5V or less at room temperature. A shunt bypass capacitor is required. During normal operation this pin is the power control. Control range varies from about 1.0V for -10dBm to 2.6V for +35dBm RF output power. The maximum power that can be achieved depends on the actual output matching; see the application information for more details. The maximum current into this pin is 5mA when VAPC1 =2.6V, and 0mA when VAPC =0V. 3 GND1 APC2 VCC NC 10 RF OUT To RF Stages GND GND Power Control for the output stage. See pin 6 for more details. See pin 6. Power supply for the bias circuits. See pin 6. Not connected. Connect this pin to the ground plane for compatibility with future packages. RF Output and power supply for the output stage. Bias voltage for the final stage is provided through this wide output pin. An external matching network is required to provide the optimum load impedance. VCC RF OUT RF OUT RF OUT 2F0 14 15 NC VCC2 16 Pkg Base 2-122 Same as pin 10. VCC2 GND From Bias GND Stages PCKG BASE Same as pin 10. Same as pin 10. Same as pin 10. Connection for the second harmonic trap. This pin is internally connected to the RF OUT pins. The bonding wire together with an external capacitor form a series resonator that should be tuned to the second harmonic frequency in order to increase efficiency and reduce spurious outputs. Not connected. Same as pin 10. U pg r 11 12 13 ad ed P 7 8 9 ro du ct R F2 17 4 S ee POWER AMPLIFIERS 2 Pin 1 Power supply for the driver stage and interstage matching. This pin forms the shunt inductance needed for proper tuning of the interstage match. Please refer to the application schematic for proper configuration, and note that position and value of the components are important. Same as pin 15. VCC2 From Bias GND2 Stages Same as pin 15. Ground connection for the output stage. This pad should be connected to the ground plane by vias directly under the device. A short path is required to obtain optimum performance, as well as to provide a good thermal path to the PCB for maximum heat dissipation. Rev A9 011031 RF2138 Theory of Operation and Application Information 3 The part will operate over a 3.0V to 5.0V range. Under nominal conditions, the power at 3.5V will be greater than +34.5dBm at +90°C. As the voltage is increased, however, the output power will increase. Thus, in a system design, the ALC (Automatic Level Control) Loop will back down the power to the desired level. This must occur during operation, or the device may be damaged from too much power dissipation. At 5.0V, over +38dBm may be produced; however, this level of power is not recommended, and can cause damage to the device. P ad ed U pg r The input is DC coupled; thus, a blocking cap must be inserted in series. Also, the first stage bias may be adjusted by a resistive divider with high value resistors on this pin to VPC and ground. For nominal operation, however, no external adjustment is necessary as internal resistors set the bias point optimally. S ee VCC1 and VCC2 provide supply voltage to the first and second stage, as well as provides some frequency selectivity to tune to the operating band. Essentially, the bias is fed to this pin through a short microstrip. A bypass capacitor sets the inductance seen by the part, so placement of the bypass cap can affect the frequency of the gain peak. This supply should be bypassed individually with 100pF capacitors before being combined with VCC for the output stage to prevent feedback and oscillations. Rev A9 011031 The HBT breakdown voltage is >20V, so there are no issue with overvoltage. However, under worst-case conditions, with the RF drive at full power during transmit, and the output VSWR extremely high, a low load impedance at the collector of the output transistors can cause currents much higher than normal. Due to the bipolar nature of the devices, there is no limitation on the amount of current de device will sink, and the safe current densities could be exceeded. High current conditions are potentially dangerous to any RF device. High currents lead to high channel temperatures and may force early failures. The RF2138 includes temperature compensation circuits in the bias network to stabilize the RF transistors, thus limiting the current through the amplifier and protecting the devices from damage. The same mechanism works to compensate the currents due to ambient temperature variations. To avoid excessively high currents it is important to control the VAPC when operating at supply voltages higher than 4.0V, such that the maximum output power is not exceeded. 2-123 2 POWER AMPLIFIERS While the part is safe under CW operation, maximum power and reliability will be achieved under pulsed conditions. The data shown in this data sheet is based on a 12.5% duty cycle and a 600µs pulse, unless specified otherwise. ro du ct The amplifier operates in near Class C bias mode. The final stage is "deep AB", meaning the quiescent current is very low. As the RF drive is increased, the final stage self-biases, causing the bias point to shift up and, at full power, draws about 2000mA. The optimum load for the output stage is approximately 1.2Ω. This is the load at the output collector, and is created by the series inductance formed by the output bond wires, vias, and microstrip, and 2 shunt capacitors external to the part. The optimum load impedance at the RF Output pad is 1.2-j1.7Ω. With this match, a 50Ω terminal impedance is achieved. The input is internally matched to 50Ω with just a blocking capacitor needed. This data sheet defines the configuration for GSM operation. The RF OUT pin provides the output power. Bias for the final stage is fed to this output line, and the feed must be capable of supporting the approximately 2A of current required. Care should be taken to keep the losses low in the bias feed and output components. A narrow microstrip line is recommended because DC losses in a bias choke will degrade efficiency and power. R F2 17 The RF2138 is a three-stage device with 32 dB gain at full power. Therefore, the drive required to fully saturate the output is +3dBm. Based upon HBT (Heterojunction Bipolar Transistor) technology, the part requires only a single positive 3V supply to operate to full specification. Power control is provided through a single pin interface, with a separate Power Down control pin. The final stage ground is achieved through the large pad in the middle of the backside of the package. First and second stage grounds are brought out through separate ground pins for isolation from the output. These grounds should be connected directly with vias to the PCB ground plane, and not connected with the output ground to form a so called “local ground plane” on the top layer of the PCB. The output is brought out through the wide output pad, and forms the RF output signal path. RF2138 Application Schematic VCC Instead of a stripline an inductor of ~10 nH can be used 120 pF Very close to pins 15/16 2 POWER AMPLIFIERS 4.3 pF 1 16 15 14 VCC 13 2 12 3 11 4 10 33 pF Quarter Wave Length .040" 50 Ω µstrip RF IN 6 7 8 18 pF 9 VCC VCC 10 nH 33 pF 5.6 pF 33 pF Spacing between edge of device and capacitor 0.062" Distance center to center of capacitors 0.416" R F2 17 5 33 pF RF OUT 1 nF 180 Ω Instead of a stripline an inductor of 4.7 nH can be used 3 1 nF 33 pF 33 pF Note: All capacitors are standard 0402 multi layer ro du ct APC Internal Schematic RF IN U pg r 5Ω 1.6k Ω 5Ω P VCC2 RF OUT 4.5 pF APC1 VCC APC2 1k Ω VCC 300 Ω S ee APC1 ad ed VCC1 GND1 2-124 GND2 PKG BASE Rev A9 011031 RF2138 Evaluation Board Schematic (Download Bill of Materials from www.rfmd.com.) P1 1 VCC1 2 VCC1 C7 1 nF 3 GND C24 120 pF C19 3.3 uF + VCC1 4 5 C6 1 nF 15 14 2 C1 1 nF R1 180 Ω 12 3 11 4 10 5 6 7 8 L1 10 nH C14 10 nF C3 1 nF C9 33 pF C2 1 nF VCC1 C10 33 pF 9 L2 8.8 nH C13 33 pF 50 Ω µstrip C21 9.1 pF C11 33 pF C5 1 nF C22 11 pF 50 Ω µstrip J2 RF OUT C23 5.6 pF C16 10 nF C4 1 nF + C17 3.3 uF J3 VPC ro du ct C8 33 pF C12 33 pF 13 3 J1 RF IN 50 Ω µstrip 16 GND 6 CON3 R F2 17 1 2 POWER AMPLIFIERS VCC1 C20 3.3 uF + VCC1 C15 10 nF + C18 3.3 uF S ee U pg r ad ed P 2138400 Rev A Rev A9 011031 2-125 RF2138 Evaluation Board Layout Board size 2.0” x 2.0” Board Thickness 0.014”; Board Material FR-4; Multi-Layer S ee U pg r ad ed P ro du ct R F2 17 3 POWER AMPLIFIERS 2 2-126 Rev A9 011031 RF2138 Typical Test Setup Power Supply V- S- S+ V+ POWER AMPLIFIERS 2 3dB 10dB/5W ro du ct Buffer x1 OpAmp Puls Generator Spectrum Analyzer R F2 17 3 RF Generator P A buffer amplifier is recommended because the current into the Vapc changes with voltage. As an alternative, the voltage may be monitored with an oscilloscope. U pg r ad ed Notes about testing the RF2138 The test setup shown above includes two attenuators. The 3dB pad at the input is to minimize the effects that the switching of the input impedance of the PA has on the signal generator. When Vapc is switched quickly, the resulting input impedance change can cause the signal generator to vary its output signal, either in output level or in frequency. Instead of an attenuator an isolator may also be used. The attenuator at the output is to prevent damage to the spectrum analyzer, and should be able to handle the power. S ee It is important not to exceed the rated supply current and output power. When testing the device at higher than nominal supply voltage, the VAPC should be adjusted to avoid the output power exceeding +36dBm. During load-pull testing at the output it is important to monitor the forward power through a directional coupler. The forward power should not exceed +36dBm, and VAPC needs to be adjusted accordingly. This simulates the behavior for the power control loop in this respect. To avoid damage, it is recommended to set the power supply to limiting the current during the burst, not to exceed the maximum current rating. Rev A9 011031 2-127 S ee U pg r ad ed P ro du ct R F2 17 3 POWER AMPLIFIERS RF2138 2 2-128 Rev A9 011031