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RF7115
QUAD-BAND GSM850/GSM900/DCS/PCS TRANSMIT MODULE
RoHS Compliant & Pb-Free Product Package Style: Module (7mmx8mm)
GSM GaAs Die LB RF IN 2
pHEMT Switch
Features
Reduced Solution Size Integrating Antenna Switch and Harmonic Filtering to Decrease Time to Market Package 7x8x1.2mm IEC 61000-4-2 Compliant In/Output Matched to 50 DC Block on Antenna Port GSM850/900 POUT =33.5dBm DCS/PCS POUT =30.5dBm New Current Limiter
VSENSE 1 B1 3 B2 4 VBATT 5 B3 6 TX EN 7 VRAMP 8 Fully Integrated Power Control Circuit and Switch Decoder 21 ANTENNA
16 RX 4 15 RX 3 14 RX 2 13 RX 1
HB RF IN 9 DCS/PCS GaAs Die
Functional Block Diagram
Applications
GSM850/EGSM900/DCS/PCS Products GPRS Class 12 Capable Power Star(c) Module 3V Quad-Band Handsets Portable Battery-Powered Equipment
Product Description
The RF7115 is a high-power, high-efficiency transmit module containing RFMD's Power Star(c) integrated power control, integrated pHEMT front end antenna switch and harmonic filtering functionality. All of which combine to provide for best in class harmonic emission control and RX and TX insertion loss. The device is self-contained with 50 input and output terminals with no matching components required. The integrated power control function based on RFMD's patented Power Star(c) control is incorporated, eliminating the need for directional couplers, detector diodes, power control ASIC's, and other power control circuitry; this allows the module to be driven directly from the DAC output. The device is designed for use as the final portion of the transmit chain in GSM850, EGSM900, DCS and PCS GMSK and eliminates the need for PA to antenna switch module matching. On-board power control provides over 70dB control range. The integrated antenna switch allows true quad band TX and RX functionality. Built-in current limiter option may be utilized to minimize power variation in mismatch condition.
Optimum Technology Matching(R) Applied
GaAs HBT GaAs MESFET InGaP HBT SiGe BiCMOS Si BiCMOS SiGe HBT GaAs pHEMT Si CMOS Si BJT GaN HEMT RF MEMS
RF MICRO DEVICES(R), RFMD(R), Optimum Technology Matching(R), Enabling Wireless ConnectivityTM, PowerStar(R), POLARISTM TOTAL RADIOTM and UltimateBlueTM are trademarks of RFMD, LLC. BLUETOOTH is a trademark owned by Bluetooth SIG, Inc., U.S.A. and licensed for use by RFMD. All other trade names, trademarks and registered trademarks are the property of their respective owners. (c)2006, RF Micro Devices, Inc.
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RF7115
Absolute Maximum Ratings Parameter
Supply Voltage Power Control Voltage (VRAMP) Input RF Power Max Duty Cycle Output Load VSWR Operating Case Temperature Storage Temperature
Rating
-0.3 to +6.0 -0.3 to +1.8 +10 50 20:1 -20 to +85 -55 to +150
Unit
V V dBm % C C
Caution! ESD sensitive device.
Exceeding any one or a combination of the Absolute Maximum Rating conditions may cause permanent damage to the device. Extended application of Absolute Maximum Rating conditions to the device may reduce device reliability. Specified typical performance or functional operation of the device under Absolute Maximum Rating conditions is not implied. RoHS status based on EUDirective2002/95/EC (at time of this document revision). The information in this publication is believed to be accurate and reliable. However, no responsibility is assumed by RF Micro Devices, Inc. ("RFMD") for its use, nor for any infringement of patents, or other rights of third parties, resulting from its use. No license is granted by implication or otherwise under any patent or patent rights of RFMD. RFMD reserves the right to change component circuitry, recommended application circuitry and specifications at any time without prior notice.
Parameter
Overall Power Control VRAMP
Power Control "ON" Power Control "OFF" VRAMP Input Capacitance VRAMP Input Current Turn On/Off Time Power Control Range VRAMP POUT BW
Min.
Specification Typ.
Max.
Unit
Condition
1.5 0.2 15 0.25 20 10 2 50 2.0 2.5 3.5 3.0 5.5 1 20
V V pF A us dB MHz V V A
Max. POUT, Voltage supplied to the input Min. POUT, Voltage supplied to the input DC to 2MHz VRAMP =VRAMP MAX VRAMP =0V to VRAMP MAX VRAMP =0.25V to VRAMP MAX
Overall Power Supply
Power Supply Voltage Power Supply Current Specifications Nominal operating limits PIN <-30dBm, TX Enable=Low, VRAMP =0V, Temp=-20C to +85C, VBATT =5.5V
Overall Control Signals
B1, B2, B3 "Low" B1, B2, B3 "High" B1, B2, B3 "High Current" TX Enable "Low" TX Enable "High" TX Enable "High Current" 0 1.25 0 1.25 0 2.0 1 0 2.0 1 0.5 3.0 2 0.5 3.0 2 V uA V V uA
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RF7115
Parameter
GSM850 Mode
Operating Frequency Range Maximum Output Power 824 33.0 32.8 31.0 Total Efficiency Input Power Range Output Noise Power 37 2 42 4 -88 <-100 Forward Isolation 1 Forward Isolation 2 All Harmonics up to 12.75GHz All Non-Harmonic Spurious Input VSWR Output Load VSWR Stability Output Load VSWR Ruggedness 10:1 20:1 -50 -29 -40 6 -83 -87 -41 -15 -35 -36 2.5:1 34.0 849 MHz dBm dBm dBm % dBm dBm dBm dBm dBm dBm dBm 25% duty cycle, pulse width 1154us 50% duty cycle, pulse width 2308us Temp=+85C, VBATT =3.0V, VRAMP = VRAMP MAX @ VBATT =3.0V At POUT MAX, VBATT =3.5V Full output power guaranteed at minimum drive level 869MHz to 894MHz, RBW=100kHz, POUT >+5dBm 1930MHz to 1990MHz, RBW=100kHz, POUT >+5dBm TXEnable=Low, PIN =+6dBm, VRAMP =0.25V, B1=B2=Low, B3=High TXEnable=High, PIN =+6dBm, VRAMP =0.25V, B1=B2=Low, B3=High Over all power levels (5dBm to 33dBm) Over all power levels (5dBm to 33dBm) Over all power levels (5dBm to 33dBm) Spurious<-36dBm, set VRAMP where POUT <33.0dBm into 50 load Set VRAMP where POUT <33.0dBm into 50 load. No damage or permanent degradation to part. 50
Min.
Specification Typ.
Max.
Unit
Condition
Temp=+25C, VBATT =3.5V, VRAMP MAX, PIN =4dBm, 25% Duty Cycle, Pulse Width=1154s
Input and Output Impedance Note: VRAMP MAX =3/8*VBATT +0.15<1.5V
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RF7115
Parameter
GSM900 Mode
Operating Frequency Range Maximum Output Power 880 33.0 32.8 31.0 Total Efficiency Input Power Range Output Noise Power 35 2 40 4 -85 -89 <-100 Forward Isolation 1 Forward Isolation 2 All Harmonics up to 12.75GHz All Non-Harmonic Spurious Input VSWR Output Load VSWR Stability Output Load VSWR Ruggedness Input and Output Impedance Note: VRAMP MAX =3/8*VBATT +0.15<1.5V 10:1 20:1 50 -60 -27 -40 6 -79 -83 -87 -41 -15 -35 -36 2.5:1 33.5 915 MHz dBm dBm dBm % dBm dBm dBm dBm dBm dBm dBm dBm 25% duty cycle, pulse width 1154us 50% duty cycle, pulse width 2308us Temp=+85C, VBATT =3.0V, VRAMP = VRAMP MAX At POUT MAX, VBATT =3.5V Full output power guaranteed at minimum drive level 925MHz to 935MHz, RBW=100kHz, POUT >+5dBm 935MHz to 960MHz, RBW=100kHz, POUT >+5dBm 1805MHz to 1880MHz, RBW=100kHz, POUT >+5dBm TXEnable=Low, PIN =+6dBm, VRAMP =0.25V, B1=High, B2=Low, B3=High TXEnable=High, PIN =+6dBm, VRAMP =0.25V, B1=High, B2=Low, B3=High Over all power levels (5dBm to 33dBm) Over all power levels (5dBm to 33dBm) Over all power levels (5dBm to 33dBm) Spurious<-36dBm, set VRAMP where POUT <33.0dBm into 50 load Set VRAMP where POUT <33.0dBm into 50 load
Min.
Specification Typ.
Max.
Unit
Condition
Temp=+25C, VBATT =3.5V, VRAMP MAX, PIN =4dBm, 25% Duty Cycle, Pulse Width=1154s
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RF7115
Parameter
DCS1800 Mode
Operating Frequency Range Maximum Output Power 1710 30.0 29.8 28.0 Total Efficiency Input Power Range Output Noise Power 32 2 37 4 -92 <-100 <-100 Forward Isolation 1 Forward Isolation 2 All Harmonics up to 12.75GHz All Non-Harmonic Spurious Input VSWR Output Load VSWR Stability Output Load VSWR Ruggedness 10:1 20:1 -60 -20 -40 6 -87 -87 -84 -53 -15 -35 -36 2.5:1 31.0 1785 MHz dBm dBm dBm % dBm dBm dBm dBm dBm dBm dBm dBm 25% duty cycle, pulse width 1154us 50% duty cycle, pulse width 2308us Temp=+85C, VBATT =3.0V, VRAMP = VRAMP MAX At POUT MAX, VBATT =3.5V Full output power guaranteed at minimum drive level 1805MHz to 1880MHz, RBW=100kHz, POUT >0dBm 925MHz to 935MHz, RBW=100kHz, POUT >0dBm 935MHz to 960MHz, RBW=100kHz, POUT >0dBm TXEnable=Low, PIN =+6dBm, VRAMP =0.25V, B1=Low, B2=High, B3=High TXEnable=High, PIN =+6dBm, VRAMP =0.25V, B1=Low, B2=High, B3=High Over all power levels (0dBm to 30dBm) Over all power levels (0dBm to 30dBm) Over all power levels (0dBm to 30dBm) Spurious<-36dBm, set VRAMP where POUT <30.0dBm into 50 load Set VRAMP where POUT <30.0dBm into 50 load. No damage or permanent degradation to part. 50
Min.
Specification Typ.
Max.
Unit
Condition
Temp=+25C, VBATT =3.5V, VRAMP MAX, PIN =4dBm, 25% Duty Cycle, Pulse Width=1154s
Input and Output Impedance Note: VRAMP MAX =3/8*VBATT +0.15<1.5V
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Parameter
PCS1900 Mode
Operating Frequency Range Maximum Output Power 1850 30.0 29.8 28.0 Total Efficiency Input Power Range Output Noise Power 32 2 37 4 -92 <-100 Forward Isolation 1 Forward Isolation 2 All Harmonics up to 12.75GHz All Non-Harmonic Spurious Input VSWR Output Load VSWR Stability Output Load VSWR Ruggedness 10:1 20:1 -60 -20 -40 6 -87 -87 -53 -15 -35 -36 2.5:1 31.0 1910 MHz dBm dBm dBm % dBm dBm dBm dBm dBm dBm dBm 25% duty cycle, pulse width 1154us 50% duty cycle, pulse width 2308us Temp=+85C, VBATT =3.0V, VRAMP = VRAMP MAX At POUT MAX, VBATT =3.5V Full output power guaranteed at minimum drive level 1930MHz to 1990MHz, RBW=100kHz, POUT >0dBm 869MHz to 894MHz, RBW=100kHz, POUT >0dBm TXEnable=Low, PIN =+6dBm, VRAMP =0.25V, B1=B2=B3=High TXEnable=High, PIN =+6dBm, VRAMP =0.25V, B1=B2=B3=High Over all power levels (0dBm to 30dBm) Over all power levels (0dBm to 30dBm) Over all power levels (0dBm to 30dBm) Spurious<-36dBm, set VRAMP where POUT <30.0dBm into 50 load Set VRAMP where POUT <30.0dBm into 50 load. No damage or permanent degradation to part. 50
Min.
Specification Typ.
Max.
Unit
Condition
Temp=+25C, VBATT =3.5V, VRAMP MAX, PIN =4dBm, 25% Duty Cycle, Pulse Width=1154s
Input and Output Impedance Note: VRAMP MAX =3/8*VBATT +0.15<1.5V
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RF7115
Parameter
RX-Section
Insertion Loss, ANT-RX1-4 Freq 869MHz to 894MHz Freq 925MHz to 960MHz Freq 1805MHz to 1880MHz Freq 1930MHz to 1990MHz Insertion Loss, ANT-RX1-4 Freq 869MHz to 894MHz Freq 925MHz to 960MHz Freq 1805MHz to 1880MHz Freq 1930MHz to 1990MHz Ripple, ANT-RX1-4 Freq 869MHz to 894MHz Freq 925MHz to 960MHz Freq 1805MHz to 1880MHz Freq 1930MHz to 1990MHz Return Loss, ANT-RX1-2 Freq 869MHz to 894MHz Freq 925MHz to 960MHz Return Loss, ANT-RX3-4 Freq 1805MHz to 1880MHz Freq 1930MHz to 1990MHz -14 -14 -12 -12 dB dB -22 -22 -15 -15 dB dB 0.02 0.02 0.06 0.06 0.20 0.20 0.20 0.20 dB dB dB dB Nominal conditions Temp=+25C, VCC =3.5V 1.4 1.4 1.7 1.7 1.7 1.7 2.0 2.0 dB dB dB dB Nominal conditions Temp=+25C, VCC =3.5V 1.0 1.0 1.3 1.3 1.3 1.3 1.6 1.6 dB dB dB dB
Min.
Specification Typ.
Max.
Unit
Condition
Nominal conditions Temp=+25C, VCC =3.5V TX=Low, B1=Low, B2=Low, B3=High TX=Low, B1=High, B2=Low, B3=X TX=Low, B1=Low, B2=High, B3=X TX=Low, B1=High, B2=High, B3=X Extreme conditions Temp=-20C, +25C, and +85C, VCC =3.0V, 3.5V, and 5.5V
Rev A0 DS060808
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RF7115
Parameter
TX-Section
Isolation, ANT-RX1-4 Freq 824MHz to 849MHz RX1 RX2 RX3 RX4 Freq 880MHz to 915MHz RX1 RX2 RX3 RX4 Freq 1710MHz to 1785MHz RX1 RX2 RX3 RX4 Freq 1850MHz to 1910MHz RX1 RX2 RX3 RX4 9.25 6.00 -5.50 6.00 10 10 10 10 dBm dBm dBm dBm Temp=+25C, VCC =3.5V, POUT =30dBm Temp=+25C, VCC =3.5V, POUT =30dBm Temp=+25C, VCC =3.5V, POUT =30dBm Temp=+25C, VCC =3.5V, POUT =30dBm 8.50 5.00 -5.00 5.50 10 10 10 10 dBm dBm dBm dBm Temp=+25C, VCC =3.5V, POUT =30dBm Temp=+25C, VCC =3.5V, POUT =30dBm Temp=+25C, VCC =3.5V, POUT =30dBm Temp=+25C, VCC =3.5V, POUT =30dBm 0.25 0.25 2.50 2.50 10 10 10 10 dBm dBm dBm dBm Temp=+25C, VCC =3.5V, POUT =33dBm Temp=+25C, VCC =3.5V, POUT =33dBm Temp=+25C, VCC =3.5V, POUT =33dBm Temp=+25C, VCC =3.5V, POUT =33dBm -0.75 -0.75 1.75 1.75 10 10 10 10 dBm dBm dBm dBm Temp=+25C, VCC =3.5V, POUT =33dBm Temp=+25C, VCC =3.5V, POUT =33dBm Temp=+25C, VCC =3.5V, POUT =33dBm Temp=+25C, VCC =3.5V, POUT =33dBm
Min.
Specification Typ.
Max.
Unit
Condition
Note: Isolation specification max limit set to ensure at least 20dB of isolation. Calculation example: POUT @ANT -POUT @RXPort, Lo Band Isolation=33-10=23dB, Hi Band Isolation=30-10=20dB. Additional RX3 circuitry ensures specification for Hi Band TX-RX overlapping frequencies. Lo Band RX-RX overlapping frequencies has sufficient margin.
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RF7115
Pin 1 Function VSENSE Description
Can provide two purposes: 1. The current limiter can be set by adding a resistor to determine the set point. When open, the current limiter feature is fully engaged and shorter the current limiter is disabled. 2. A voltage proportional to the PA current can be detected and used as feedback to the baseband. See application note for further details. RF input to the GSM850/GSM900 band. This is a 50 input.
Interface Schematic
2
GSM850/ GSM900 IN
3 4 5 6 7
B1 B2 VBATT B3 TX ENABLE
Control pin that together with B2 and B3 selects band of operation. Control pin that together with B1 and B3 selects band of operation. Power supply for the module. This should be connected to the battery terminal using as wide a trace as possible. Control pin that together with B1 and B2 selects band of operation. This signal enables the PA module for operation with a logic high. The switch is put in TX mode determined by B1, B2, and B3.
TX ENABLE
TX ON
8
VRAMP
VRAMP ramping signal from DAC. A simple RC filter may need to be connected between the DAC output and the VRAMP input depending on the baseband selected.
+
9
DCS/PCS IN
DCS/PCS IN RF input to the DCS/PCS band. This is a 50 input.
HB RF IN
10 11 12 13 14 15
GND GND GND RX 1 RX 2 RX 3
RX 1 port of antenna switch. This is a 50 output. Note that there will be a DC voltage present equal to VBATT -0.5V. RX 2 port of antenna switch. This is a 50 output. Note that there will be a DC voltage present equal to VBATT -0.5V. RX 3 port of antenna switch. This is a 50 output. Note that there will be a DC voltage present equal to VBATT -0.5V. Additional logic provided to improve isolation at 2f0 of GSM band.
RX850
RX900
RX1800
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RF7115
Pin 16 17 18 19 20 21 Function RX 4 GND GND GND GND ANT Description
RX 4 port of antenna switch. This is a 50 output. Note that there will be a DC voltage present equal to VBATT -0.5V.
Interface Schematic
RX1900
Antenna port of antenna switch. This is a 50 output. Provides DC blocking as well as ESD protection.
ANTENNA
22 23 Pkg Base
GND GND GND
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RF7115
Theory of Operation
Product Description The RF7115 is a high-power, high-efficiency, transmit module (TXM) with fully-integrated power control functionality, harmonic filtering, band selectivity, and TX/RX switching. The TXM is self-contained, with 50 I/O terminals with four RX ports allowing true quad band operation. The power control function eliminates all power control circuitry, including directional couplers, diode detectors, and power control ASIC's, etc. The power control capability provides 50dB continuous control range, and 70dB total control range, using a DAC-compatible, analog voltage input. The TX Enable feature provides for PA activation (TX mode) or RX mode/Stand-by. Internal switching provides a low-loss, low-distortion path from the Antenna port to the TX path (or RX port), while maintaining proper isolation. Integrated filtering provides ETSI compliant harmonic suppression at the antenna port even under high mismatch conditions, which is important as modern antennas today often present a load that significantly deviates from nominal impedance. Overview The RF7115 is a true quad-band GSM850, EGSM900, DCS1800, and PCS1900 power amplifier module with fully integrated power control functionality, harmonic filtering, band selectivity and TX/RX switching. This simplifies the phone design by eliminating the need for the complicated control loop design, harmonic filters, TX/RX switch and possible matching components between these. The power control loop can be driven directly from the DAC output in the baseband circuit. The module has 4 Rx ports for GSM850. EGSM900, DCS1800, and PCS1900 bands of operation. For optimum performance, it is best to use Rx1 and Rx2 for low band, and Rx3 and Rx4 for high band operation. Best forward isolation can be achieved in these states during the off mode as well. To control the mode of operation, there are four logic control signals; TX Enable, B1, B2, and B3. Refer to truth table below for mode of operations. If control signals are limited, eliminate the use of the standby mode and B3 may remain in the high state for all modes of operation. By also changing the don't care state (X) of B1 allows minimum control logic switching between on and off states. Module Control and Antenna Switch Logic TX_EN
0 0 0 0 0 1 1
B1
0 0 1 0 1 x x
B2
0 0 0 1 1 0 1
B3
0 1 x x x 1 1
TX Module Mode
Stand by mode RX 1 RX 2 RX 3 RX 4 TX low band (GSM850/EGSM900) TX high band (DCS1800/PCS1900)
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RF7115
Power Control Theory of Operation Most power control systems in GSM sense either forward power or collector/drain current. The RF7115 uses RFMD's Power StarR collector voltage control instead of a power or current detector. A high-speed control loop is incorporated to regulate the collector voltage of the amplifier while the stages are held at a constant bias. The basic circuit is shown in the following diagram.
VBATT TX ENABLE VRAMP
H(s)
RF IN
RF OUT
By regulating the power, the stages are held in saturation across all power levels. As the required output power is decreased from full power down to -15dBm, the collector voltage is also decreased. This regulation of output power is demonstrated in Equation 1 where the relationship between collector voltage and output power is shown. Although load impedance affects output power, supply fluctuations are the dominate mode of power variations. With the RF7115 regulating, there are several key factors to consider in the implementation of a transmitter solution for a mobile phone. Some of them are:
P dBm
* * * * * * * * * * * * * * * * *
( 2 V CC - V SAT ) = 10 log -------------------------------------------3 8 R LOAD 10
2
(Eq. 1)
Effective efficiency (EFF) Current draw and system efficiency Power variation due to Supply Voltage Power variation due to frequency Power variation due to temperature Input impedance variation Noise power Loop stability Loop bandwidth variations across power levels Burst timing and transient spectrum trade offs Harmonics Post PA loss Insertion loss in receive ports TX power leakage into the RX ports Performance during VSWR Time needed to implement the solution Needed board area for the solution
Talk time and power management are key concerns in transmitter design since the power amplifier is the leading current consumer in a mobile terminal. Considering only the power amplifier's efficiency does not provide a true picture for the total system efficiency. It is important to consider effective efficiency which is represented by EFF. (EFF considers the loss between the PA and antenna and is a more accurate measurement to determine how much current will be drawn in the application). EFF is defined by the following relationship (Equation 2):
10 - 10 EFF = -----------------------------------------------V BAT I BAT 10
P PA + P LOSS ----------------------------10
P IN ------10
(Eq. 2)
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RF7115
Where PPA is the output power from the PA, PLOSS the insertion loss and PIN the input power to the PA. The RF7115 improves the effective efficiency by minimizing the PLOSS term in the equation. An ASM may have a typical loss of 1.2dB in LB and 1.4dB in high band. To be added to this is trace losses and mismatch losses. A post PA loss of 1.5dB in LB and 1.8dB in HB is common. With the integration of a low loss pHEMT switch and matching network in the same module, higher system efficiency can be achieved. Output power does not vary due to supply voltage under normal operating conditions if VRAMP is sufficiently lower than VBATT. By regulating the collector voltage to the PA the voltage sensitivity is essentially eliminated. This covers most cases where the PA will be operated. However, as the battery discharges and approaches its lower power range the maximum output power from the PA will also drop slightly. In this case, it is important to also decrease VRAMP to prevent the power control from inducing switching transients. These transients occur as a result of the control loop slowing down and not regulating power in accordance with VRAMP. The relationship for VRAMPMAX based on VBATT is expressed in equation 3.
3 V RAMPMAX = -- x V BATT + 0.15 1.5V 8
(Eq. 3)
The components following the power amplifier often have insertion loss variation with respect to frequency. Usually, there is some length of microstrip that follows the power amplifier. There is also a frequency response found in directional couplers due to variation in the coupling factor over frequency, as well as the sensitivity of the detector diode. Since the RF7115 does not use a directional coupler with a diode detector, these variations do not occur. Also the TX/RX switch with low pass filters that usually follows the PA may contribute to frequency variation. The TX/RX switch incorporated in the RF7115 is very broadband and does not contribute to frequency roll off. Traditionally working with PA modules, some matching network is necessary between the PA output and the input of the TX/RX switch in order to get best possible performance. This work no longer has to be carried out, as this matching network is included in the RF7115. Noise power in PA's where output power is controlled by changing the bias voltage is often a problem when backing off of output power. The reason is that the gain is changed in all stages and according to the noise formula (Equation 4),
--------------- F3 - 1 F TOT = F1 + F2 - 1 + ------------------G1 G2 G1
(Eq. 4)
the noise figure depends on noise factor and gain in all stages. Because the bias point of the RF7115 is kept constant the gain in the first stage is always high and the overall noise power is not increased when decreasing output power. Power control loop stability often presents many challenges to transmitter design. Designing a proper power control loop involves trade-offs affecting stability, transient spectrum and burst timing. The RF7115 loop bandwidth is determined by internal bandwidth and does not change with respect to power levels. This makes it easier to maintain loop stability with a high bandwidth loop since the bias voltage and collector voltage do not vary. An often overlooked problem in PA control loops is that a delay not only decreases loop stability it also affects the burst timing when, for instance the input power from the VCO decreases (or increases) with respect to temperature or supply voltage. The burst timing then appears to shift to the right especially at low power levels. The RF7115 is insensitive to a change in input power and the burst timing is constant and requires no software compensation. Switching transients occur when the up and down ramp of the burst is not smooth enough or suddenly changes shape. If the control slope of a PA has an inflection point within the output power range or if the slope is simply too steep it is difficult to prevent switching transients. Controlling the output power by changing the collector voltage is as earlier described based on the physical relationship between voltage swing and output power. Furthermore all stages are kept constantly biased so inflexion points are nonexistent. Harmonics are natural products of high efficiency power amplifier design. An ideal class "E" saturated power amplifier will produce a perfect square wave. Looking at the Fourier transform of a square wave reveals high harmonic content. Although this is common to all power amplifiers, there are other factors that contribute to conducted harmonic content as well. With most power control methods a peak power diode detector is used to rectify and sense forward power. Through the rectification process there is additional squaring of the waveform resulting in higher harmonics. The RF7115 address this by eliminating the need for the detector diode. Therefore the harmonics coming out of the PA should represent the maximum power of the harmonics throughout the transmit chain. This is based upon proper harmonic termination of the transmit port.
Rev A0 DS060808
7628 Thorndike Road, Greensboro, NC 27409-9421 * For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
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RF7115
Performance under VSWR Often overlooked when designing transmitters is the fact that they normally operate under mismatch conditions while they are designed to operate only under perfect 50 ohm loads. This means that in the real application, performance is degraded. This performance degradation may include reduction in output power, increased harmonic levels, increased transient spectrum and catastrophic failures, breakdown. Traditionally designers have verified that the PA does not break during mismatch and this is all verification that has been carried out during mismatch. Modern antennas in handsets often present a load that significantly deviates from nominal impedance. A VSWR of 5:1 in not uncommon. In order not to disturb other phones in the same and close by cells, it is important that the ETSI specifications for transient spectrum, bust timing and spurious emission are fulfilled even during mismatch conditions. The RF7115 is designed to maintain its performance even under high antenna mismatch conditions. If power variation into a mismatch condition presents a problem, a current limiting option maybe utilized. The current limiter can be set by adding a resistor to determine the set point. When open, the current limiter feature is fully engaged and shorter the current limiter is disabled. Please refer to application note for further details. Unlike a current controlled power control loop, the voltage controlled loop is almost impossible to force out of lock. For the current controlled loop this easily happens as the current to the power amplifier that the controller tries to keep constant can not be maintained during some phase angles. If the output stage of the power amplifier faces a high impedance due to mismatch at the antenna, then the last stage simply cannot sink the current it does in a 50 load condition. As the loop detects the lower current, the control voltage to the power amplifier increases in an attempt to keep the current constant. As it is impossible to reach the desired current, the control voltage for the power amplifier rails and the error is accumulated in the integrator in the control loop. When the reference value is lowered when the down ramp starts, the integrator still contains the accumulated error and the control voltage to the power amplifier does not track the reference signal. This means that the burst will be too long and that when the error finally reaches zero in the integrator, the control voltage to the power amplifier suddenly decreases and this will contribute to increased levels of transient spectrum at the down ramp. The Power Star methodology is superior to the traditional current control method; it allows the transient spectrum in normal operation to be in the order of -35dBm to -40dBm but also both transient spectrum and the power versus time performance is unaffected even with severe mismatch. In addition to this, the harmonics of the RF7115 is designed to be within ETSI limits for usage with realistic antennas. TX/RX Switch The pHEMT switch integrated in the RF7115 allows for a low loss connection between the antenna port and the four RX ports. The insertion loss in the TX and RX paths is lower than the loss for a traditional pin-diode switch solution, which means lower current consumption in TX mode and better receiver sensitivity.
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RF7115
Package Drawing
1
1.14 0.040
8.000 0.10
7.000 0.10 Shaded areas represent pin 1.
Dimensions in mm.
0.600 TYP
5.365 5.535 TYP 6.000 TYP
1
7.800 TYP 7.350 TYP 6.485 6.315 5.685 5.550 4.885 TYP 4.150 3.350 TYP 2.625 TYP 2.550 TYP 1.750 TYP 0.950 TYP 0.200 TYP 0.150 TYP 0.000 0.100 TYP 0.665 TYP 1.000 TYP 0.000 3.050 TYP 3.350 TYP 5.300 5.600 TYP 6.100 TYP 6.400 TYP 6.900 TYP
7.850 TYP 7.285 TYP 7.115 7.050 TYP 6.250 TYP 5.750 TYP 5.450 TYP 5.250 TYP 4.650 TYP 3.850 TYP 3.050 TYP 2.325 TYP 2.250 TYP 1.450 TYP 0.950 TYP 0.950 0.650 TYP
Package Style: Module (7mmx8mm)
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7628 Thorndike Road, Greensboro, NC 27409-9421 * For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
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RF7115
Pin Out
GND
VSENSE
1
22
21
ANT
LB_RFIN
2
GND
GND
20
GND
B1
3 23
23
19
GND
B2
4
18
GND
VBAT
5 GND GND
17
GND
B3
6
16
RX4
TX_EN
7
23 23
23 23
15
RX3
VRAMP
8 GND GND
14
RX2
HB_RFIN
9
13
RX1
GND
10
11 GND
12
GND
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RF7115
Application Schematic
22 LB RF IN VSENSE B1 B2 VBATT 4.7 uF 50 strip Customer Option. See Application Note. 2 1 3 4 5 6 7 8
Optional depending on BB selection
pHEMT Switch
21 16 - 20
50 strip
Fully Integrated Power Control Circuit and Switch Decoder
33 pF 16 15 14 13 33 pF RX3 33 pF RX2 33 pF RX1 RX4
B3 TXEN VRAMP
HB RFIN
50 strip
9 10 11 GND: Internally connected to HB Q2 De-coupling Capacitor requires external GND 12 GND: Connected to backside GND
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7628 Thorndike Road, Greensboro, NC 27409-9421 * For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
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RF7115
Evaluation Board Schematic
P3 1 GND P2-1 P1-1 P1-2 P1-3 P1-4 P1-5 P2 1 1 2 3 4 5 6 P1-7 P1-8 7 8 P1 GND R1 10 k B2 R2 10 k B3 R3 10 k R4 10 k R6 0 B1 VRAMP LXEN 8 7 6 5 SW-DIP4 S1 1 2 3 4 C11 10 uF C10 10 uF 8 7 6 5 U2 VOUT1 VOUT2 ERROR1 ERROR2 VIN SD1 SD2 GND 1 2 3 4
23 1 J4 LB RFIN B1 B2 VBATT + C6 4.7 uF C7* DNI + C3* DNI B3 J9 TXEN VRAMP J10 VRAMP C12* DNI R5 0 J6 HB RFIN 2 3 4 5 6 7 8 9 10 11 U1 RF7115 22 21 20 19 18 17 16 15 14 13 12 C5 33 pF C2 33 pF C4 33 pF C1 33 pF J2 ANT
TXEN
J3 RX4 J5 RX3 J7 RX2 J8 RX1
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RF7115
Evaluation Board Layout Board Size 2.0" x 2.0"
Board Thickness 0.052", Board Material FR-4, Multi-layer
Assembly Top
Inner 1
Inner 2
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7628 Thorndike Road, Greensboro, NC 27409-9421 * For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
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RF7115
Inner 3 Inner 4
Back
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RF7115
PCB Design Requirements
PCB Surface Finish The PCB surface finish used for RFMD's qualification process is electroless nickel, immersion gold. Typical thickness is 3inch to 8inch gold over 180inch nickel. PCB Land Pattern Recommendation PCB land patterns for RFMD components are based on IPC-7351 standards and RFMD empirical data. The pad pattern shown has been developed and tested for optimized assembly at RFMD. The PCB land pattern has been developed to accommodate lead and package tolerances. Since surface mount processes vary from company to company, careful process development is recommended. PCB Metal Land and Solder Mask Pattern
A = 0.50 Sq. Typ. A = 0.65 Sq. Typ. B = 2.65 x 2.62 C = 2.05 x 2.25 D = 2.05 x 2.62 E = 2.05 x 2.12 5.87 Typ.
Dimensions in mm.
0.42 Typ.
A 6.40 5.60 4.80 4.00 3.20 Typ. 2.40 Typ. 1.60 Typ. 0.80 Typ. 0.42 0.00 A A A A A A A A A A
A
7.45 Typ. 6.81
7.20 Typ. 6.73 6.40 Typ. 5.60 Typ. 4.80 Typ.
A A A A A A A A A A
A C
A A A A A B D A A A E A A
7.40 Typ. 6.27 5.15 Typ.
3.75 A A A A 0.25
4.00 Typ. 3.20 Typ. 2.40 Typ. 1.60 Typ. 0.80 Typ. 0.49 0.00
3.53 Typ.
1.92 Typ. 0.86
A
6.55 Typ.
0.00
0.80 1.22
0.00
0.80 Typ. 1.28 Typ.
3.30 Typ.
4.62 Typ.
Metal Land Pattern
Solder Mask Pattern
Ordering Information
RF7115Quad-Band GSM850/GSM900/DCS/PCS Transmit Module
RF7115SB
RF7115PCBA-41X
Power Amp Module 5-Piece Sample Pack blaPower Amp Module 5-Piece Sample Pack blaPower Amp Module 5-Piece Sample Pack bla Fully Assembled Evaluation Board
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7628 Thorndike Road, Greensboro, NC 27409-9421 * For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
6.30 Typ.
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RF7115
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