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CX77304-15
PA Module for Dual-band GSM850 PCS1900 / GPRS Applications
The CX77304-15 Power Amplifier Module(PAM) is designed in a compact form factor for dual-band cellular handsets comprising GSM850 and PCS1900 operation. It also supports Class 10 General Packet Radio Service (GPRS) multislot operation.
Distinguishing Features
* * * * High efficiency GSM 55% PCS 45% Input/output internally matched to 50 Small outline 9.1 mm x 11.6 mm Low profile 1.5 mm maximum Low APC current 10 A, typical Gold plated, lead-free contacts
The module consists of separate Heterojunction Bipolar Transistor (HBT) PA blocks for the GSM850 and PCS1900 bands, interface circuitry, and RF input and output ports internally matched for 50 impedance to reduce the number of external components. The PA blocks are fabricated on a single Gallium Arsenide (GaAs) die * and share common power supply pins for current distribution. Extremely low * leakage current (2 A, typical) of the dual PA module maximizes handset standby time. *
The CX77304-15 also contains band-select switching circuitry to select GSM (logic 0) and PCS (logic 1) as determined from the Band Select (BS) signal. In the * block diagram shown below, the BS pin selects the PA output (PCS OUT or Applications GSM OUT) while the Analog Power Control (APC) controls the level of output power.
A custom CMOS IC provides the internal interface circuitry including a current amplifier that minimizes the required power control current (IAPC) to 10 A, typical. The GaAs die, the Silicon (Si) die, and passive components are mounted on a multi-layer laminate substrate and the assembly encapsulated with plastic overmold.
*
Dual-band cellular handsets encompassing Class 4 GSM850 PCS1900, and up to Class 10 GPRS multislot operation
Functional Block Diagram
HBT
PCS IN
Match
Match
PCS OUT
Power Control Band Select
CMOS Bias Controller
GSM IN
Match
Match
GSM OUT
Data Sheet (c) 2001-2003 Skyworks Solutions, Inc., All Rights Reserved.
101749A September 19, 2003
Electrical Specifications
CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Electrical Specifications
The following tables list the electrical characteristics of the CX77304-15 Power Amplifier. Table 1 lists the absolute maximum ratings and Table 2 shows the recommended operating conditions. Table 3 shows the electrical characteristics of the CX77304-15 for GSM and PCS modes. A typical CX77304-15 application diagram appears in Figure 1. The CX77304-15 is a static-sensitive electronic device and should not be stored or operated near strong electrostatic fields. Detailed ESD precautions along with information on device dimensions, pin descriptions, packaging and handling can be found in later sections of this data sheet.
Table 1. Absolute Maximum Ratings Parameter
Input Power (PIN) Supply Voltage (VCC), Standby, VAPC 0.3 V Control Voltage (VAPC) Storage Temperature
Minimum
-- -- -0.5 -55
Maximum
15 7 VCCMAX - 0.2 (See Table 3) +100
Unit
dBm V V C
Table 2. Recommended Operating Conditions Parameter
Supply Voltage (VCC) Supply Current (ICC) Operating Case Temperature (TCASE) 1-Slot (12.5% duty cycle) 2-Slot (25% duty cycle) 3-Slot (37.5% duty cycle) 4-Slot ( 50% duty cycle)
NOTE(S):
(1)
Minimum
2.8 0
Typical
3.2 -- --
Maximum
4.6V(1) 2.5(1)
Unit
V A C
-20 -20 -20 -20
100 90 75 60
For charging conditions with VCC > 4.6 V, derate ICC linearly down to 0.5 A max at VCC = 5.5 V.
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CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Electrical Specifications
Table 3. CX77304-15 Electrical Specifications(1) (1 of 3) Parameter Symbol Test Condition General
Supply voltage Power Control Current Leakage Current VCC IAPC Iq VCC = 4.5 V VAPC = 0.3 V TCASE = +25 C PIN -60 dBm -- Time from VAPC VAPCTH until POUT (POUT_FINAL - 3 dB) -- -- 2.8 -- -- 3.2 10 -- 4.6 100 5 V A A
Min
Typical
Max
Units
APC Enable Threshold APC Enable Switching Delay
VAPCTH tSW
200 5
--
600 8
mV s
GSM Mode (f = 824 to 849 MHz and PIN = 6 to 10 dBm)
Frequency range Input power Analog power control voltage Power Added Efficiency f PIN VAPC PAE POUT = 32 dBm VCC = 3.2 V POUT 34.0 dBm VAPC 2.0 V, pulse width 577 s, duty cycle 1:8 TCASE = +25 C BW = 3 MHz 5 dBm POUT 35 dBm VCC = 3.2 V VAPC 2.0 V TCASE = +25 C VCC = 2.8 V VAPC 2.6 V TCASE = -20 C to +100 C (See Table 2 for multislot) PIN = 6 dBm VCC = 4.6 V VAPC 2.6 V TCASE = -20 C to +100 C (See Table 2 for multislot) PIN = 6 dBm POUT = 5 to 35 dBm, controlled by VAPC PIN = 10 dBm VAPC = 0.3 V -- -- 824 6 1.2 50 -- -- 1.7 55 849 10 2.1 -- MHz dBm V %
2nd to 13th harmonics Output power
2f0 to 13f0 POUT
-- 34.0
-- 34.5
-7 --
dBm dBm
POUTMAX LOW VOLTAGE
32
33
--
dBm
POUTMAX HIGH VOLTAGE
32
33
--
dBm
Input VSWR Forward isolation
IN POUTSTANDBY
-- --
1.5:1 -35
2.2:1 -30
-- dBm
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Electrical Specifications
CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Table 3. CX77304-15 Electrical Specifications(1) (2 of 3) Parameter
Spurious
Symbol
Spur
Test Condition
No parasitic oscillation with all combinations of the following parameters: VAPC = controlled(2) PIN = 10.0 dBm VCC = 2.8 V to 4.6 V Load VSWR = 6:1, all phase angles step input of VAPC to RF output power within 1 dB of final value starting state: VAPC = 0.6 V
Min
--
Typical
--
Max
-36
Units
dBm
Output Power Switching Speed
--
--
3 s
dBm
Load mismatch
Load
All combinations of the following parameters: VAPC = controlled(2) PIN = 10 dBm VCC = 2.8 V to 4.6 V Load VSWR = 10:1, all phase angles At f0 + 20 MHz T = 25 C RBW = 100 kHz VCC = 3.2 V PIN = 6 dBm POUT = 34.0 dBm At f0 + 10 MHz T = 25 C RBW = 100 kHz VCC = 3.2 V PIN = 6 dBm POUT = 34.0 dBm At 1930 to 1990 MHz RBW = 100 kHz VCC = 3.2 V POUT = 34.0 dBm
No module damage or permanent degradation
Noise power
PNOISE
--
--
-84
dBm
--
--
-76
dBm
--
--
-90
dBm
PCS Mode (f = 1850 to 1910 MHz and PIN = 6 to 10 dBm)
Frequency range Input power Analog power control voltage Power Added Efficiency f PIN VAPC PAE POUT = 29.5 dBm VCC = 3.2 V POUT 32 dBm VAPC 2.0 V, pulse width 577 s, duty cycle 1:8 TCASE = +25 C BW = 3 MHz 5 dBm POUT 32 dBm -- -- 1850 6 1.35 42 -- -- 1.7 45 1910 10 2.1 -- MHz dBm V %
2nd to 7th harmonics
2f0 to 7f0
--
--
-7
dBm
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CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Table 3. CX77304-15 Electrical Specifications(1) (3 of 3) Parameter
Output power POUT
Electrical Specifications
Symbol
Test Condition
VCC = 3.2 V VAPC 2.0 V TCASE = +25 C VCC = 2.8 V VAPC 2.6 V T = 25 C (See Table 2 for multislot) PIN = 6 dBm VCC = 2.8 V VAPC 2.6 V TCASE = -20 C to +100 C (See Table 2 for multislot) PIN = 6 dBm POUT = 0 to 32 dBm controlled by VAPC PIN = 10 dBm, VAPC = 0.3 V step input of VAPC to RF output power within 1 dB of final value starting state: VAPC = 0.6 V No parasitic oscillation with all combinations of the following parameters: VAPC = controlled(3) PIN = 10.0 dBm VCC = 2.8 V to 4.6 V Load VSWR = 6:1, all phase angles All combinations of the following parameters: VAPC = controlled(3) PIN = 10 dBm VCC = 2.8 V to 4.6 V Load VSWR = 10:1, all phase angles At f0 + 20 MHz T = +25 C RBW = 100 kHz VCC = 3.2 V POUT = 32 dBm At 869 to 894 MHz RBW = 100 kHz VCC = 3.2 V POUT = 32 dBm
Min
32
Typical
32.5
Max
--
Units
dBm
POUTMAX LOW VOLTAGE
30.0
30.5
--
dBm
POUTMAX HIGH VOLTAGE
29.0
30.5
--
dBm
Input VSWR Forward isolation Switching time
IN POUTSTANDBY RISE, FALL
-- -- --
-- -40 --
2:1 -35 3 s
-- dBm dBm
Spurious
Spur
--
--
-36
dBm
Load mismatch
Load
No module damage or permanent degradation
Noise power
PNOISE
--
--
-77
dBm
--
--
-84
dBm
NOTE(S):
(1)
Unless specified otherwise: TCASE = -20 to max. operating temperature (see Table 2), RL = 50, pulsed operation with pulse width 2308 s and duty cycle 4:8, VCC = 2.8 V to 4.6 V. (2) ICC = 0A to xA, where x = current at POUT = 34.0 dBm, 50 load, and VCC = 3.2 V. (3) ICC = 0A to xA, where x = current at POUT = 32.0 dBm, 50 load, and VCC = 3.2 V.
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Electrical Specifications
CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Figure 1. Typical CX77304-15 Application
C 10 F ELECTROLYTIC VBAT
10 pF B APC from PAC B
PCS IN APC IN 2 Match
HBT
PCS OUT Match 12 CMOS Bias Controller
10 pF
14
CX77304-15
BS IN (from Baseband)
16 Match Match
GSM OUT 10
33 pF
4 GSM IN
6 VCC C VCC1
8 VCC2 100 pF A 10 nF A
9 GND
A Place caps at closest proximity to PA module with the
capacitor ground directly connected to the PAM grounds.
B C
Optional depending on PAC circuit. Common connect Vbat to all Vcc pins.
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CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Package Dimensions and Pin Descriptions
Package Dimensions and Pin Descriptions
Figure 2 is a mechanical diagram of the pad layout for the 16-pin leadless CX77304-15 dual-band PA module. Figure 3 provides a recommended phone board layout footprint for the PAM to help the designer attain optimum thermal conductivity, good grounding, and minimum RF discontinuity for the 50 ohm terminals. Figure 4 shows the pin configuration and pin numbering convention, which starts with pin 1 in the upper left, as indicated, and increments counter-clockwise around the package. Table 4 lists the pin names and descriptions. Figure 5 interprets typical case markings.
Figure 2. CX77304-15 Package Dimensions-16-pin Module (All Views)
R0.381 Typ 0.762 Typ R0.860 Typ 0.127 Ref
Pin 1
2.286 0.051
9.10 +0.20/ -0.08
1.905 0.051 2.286 0.051
0.737 0.051 TOP VIEW SIDE VIEW 3.899 0.051
1.905 0.051 BOTTOM VIEW 11.60 +0.20/-0.08
1.02 Typ
1.50 max. FRONT VIEW
NOTE(S): 1. All contact points are gold plated, lead free-surfaces. 2. All dimensions are in millimeters.
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Package Dimensions and Pin Descriptions
CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Figure 3. Phone Board Layout Footprint for 9.1 mm x 11.6 mm Package
1.42 0.86
PIN 1 PIN 16
1.42 0.86
PIN 1 PIN 16
1.8 1 3.20 9.8
0.3
9.8
5.00
1.905
1.91
Component Outline
12.3
12.3 Component Outline
STENCIL APERTURE
TOP VIEW APPROACH 1
STENCIL APERTURE
TOP VIEW APPROACH 2
Common Ground Pad 1.32 0.05 ALL AROUND 0.762
PIN 1 PIN 16
1.42
PIN 16
0.86
PIN 1
9.70
4.5
9.8
1.905 TYP
1.91 TYP
4X 0.82 12.20 Component Outline 0.250 7 12.3 Component Outline SOLDER MASK OPENING
TOP VIEW
METALLIZATION
TOP VIEW
Thermal Via Array o 0.3 mm on 0.8 mm pitch / Additional vias will improve thermal performance. NOTE: Thermal vias should be tented and filled with solder mask, 30-35 m Cu plating recommended.
101749_006
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CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Package Dimensions and Pin Descriptions
Figure 4. CX77304-15 Pin Configuration--16-Pin Leadless Module (Top View)
GND
GND
1
16
15
14
APC
BS
13 GND
PCS IN
2
12 PCS OUT
GND
3
11 GND
GSM IN
4
10 GSM OUT
GND
5
6 VCC
7 GND
8 VCC
9 GND
Table 4. CX77304-15 Signal Description Pin
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 GND PCS IN GND GSM IN GND VCC GND VCC GND GSM OUT GND PCS OUT GND APC GND BS
Name
Ground
Description
RF input to PCS PA (DC coupled) Ground RF input to GSM PA Ground Power supply for PA driver stages Ground Power supply for PA output stages Ground GSM RF output (DC coupled) Ground PCS RF output (DC coupled) Ground Analog Power Control Ground Band Select
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Package Dimensions and Pin Descriptions
CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Figure 5. Typical Case Markings
Mark Pin 1 Identifier
SKYWORKS
CX77304-NN KXXXXX.XX YYWW MEX
Manufacturing Part Number-Revision Number Lot Number YY = Manufacture Year WW = Week Package Sealed MEX = Country Code
101749_008
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101749A September 19, 2003
CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Package and Handling Information
Package and Handling Information
Because of its sensitivity to moisture absorption, this device package is baked and vacuum packed prior to shipment. Instructions on the shipping container label must be followed regarding exposure to moisture after the container seal is broken, otherwise, problems related to moisture absorption may occur when the part is subjected to high temperature during solder assembly. The SKY77304-15 is capable of withstanding an MSL 3/240 C solder reflow. Care must be taken when attaching this product, whether it is done manually or in a production solder reflow environment. If the part is attached in a reflow oven, the temperature ramp rate should not exceed 5 C per second; maximum temperature should not exceed 240 C. If the part is manually attached, precaution should be taken to insure that the part is not subjected to temperatures exceeding 240 C for more than 10 seconds. For details on attachment techniques, precautions, and handling procedures recommended by Skyworks, please refer to Application Note: PCB Design and SMT Assembly/Rework, Document Number 101752. Additional information on standard SMT reflow profiles can also be found in the JEDEC Standard J-STD-020B. Production quantities of this product are shipped in the standard tape-and-reel format. For packaging details, refer to Application Note: Tape and Reel, Document Number 101568.
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Electrostatic Discharge Sensitivity
CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Electrostatic Discharge Sensitivity
The CX77304-15 is a Class I device. Figure 6 lists the Electrostatic Discharge (ESD) immunity level for each pin of the CX77304-15 product. The numbers in Figure 6 specify the ESD threshold levels for each pin where the I-V curve between the pin and ground starts to show degradation. The ESD testing was performed in compliance with MIL-STD-883E Method 3015.7 using the Human Body Model. If ESD damage threshold magnitude is found to consistently exceed 2000 volts on a given pin, this so is indicated. If ESD damage threshold below 2000 volts is measured for either polarity, numbers are indicated that represent worst case values observed in product characterization.
Figure 6. ESD Sensitivity Areas (Top View)
> +2000 V < -2000 V BS GND 1 16 > +2000 V < -2000 V APC 14 13 GND
GND 15
PCS IN > +2000 V < -2000 V GND
2
12
PCS OUT > +2000 V < -2000 V GND
3
11
GSM IN + 1800 V - 1950 V GND
4
10
GSM OUT > +2000 V < -2000 V GND
5
6 VCC > +2000 V < -2000 V
7 GND
8 VCC > +2000 V < -2000 V
9
101749_007
Various failure criteria can be utilized when performing ESD testing. Many vendors employ relaxed ESD failure standards which fail devices only after "the pin fails the electrical specification limits" or "the pin becomes completely non-functional". Skyworks employs most stringent criteria, fails devices as soon as the pin begins to show any degradation on a curve tracer. To avoid ESD damage, both latent and visible, it is very important that the product assembly and test areas follow the Class-1 ESD handling precautions listed in Table 5.
Table 5. Precautions for Handling GaAs IC-based Products to Avoid Induced Damage
Personnel Grounding Wrist Straps Conductive Smocks, Gloves and Finger Cots Antistatic ID Badges Protective Workstation Dissipative Table Tops Protective Test Equipment (Properly Grounded) Grounded Tip Soldering Irons Conductive Solder Suckers Static Sensors Facility Relative Humidity Control and Air Ionizers Dissipative Floors (less than 109 to GND) Protective Packaging & Transportation Bags and Pouches (Faraday Shield) Protective Tote Boxes (Conductive Static Shielding) Protective Trays Grounded Carts Protective Work Order Holders
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CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Technical Information
Technical Information
CMOS Bias Controller Characteristics
The CMOS die within the PAM performs several functions that are important to the overall module performance. Some of these functions must be considered for development of the power ramping features in a 3GPP compliant transmitter power control loop1. Power ramping considerations will be discussed later in this section. The four main functions that will be described in this section are Standby Mode Control, Band Select, Voltage Clamp, and Current Buffer. The functional block diagram is shown in Figure 7.
Figure 7. Functional Block Diagram
Band Select (pin16)
vodcs
CComp
APC input (pin14)
Supply (pin6)
cpgsm vogsm
CComp
cpdcs
Combinational Logic Voltage Clamp
Bandgap Reference
CMOS bias controller
PCS1900 bias out Ground Cbypass Cbypass GSM850 bias out
RF Isolation
RF Isolation
Dual Band GaAs Power Amplifier Die
101749_011
1.
Please refer to 3GPP TS 05.05, Digital Cellular Communications System (Phase 2+); Radio Transmission and Reception. All GSM specifications are now the responsibility of 3GPP. The standards are available at http://www.3GPP.org/specs/specs.htm
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Technical Information
CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Standby Mode Control
The Combinational Logic cell includes enable circuitry that monitors the APC ramping voltage from the power amplifier controller (PAC) circuit in the GSM transmitter. Typical handset designs directly connect the PA VCC to the battery at all times, and for some PA manufacturers this requires a control signal to set the device in or out of standby mode. The Skyworks PAM does not require a Transmit Enable input because it contains a standby detection circuit that senses the VAPC to enable or disable the PA. This feature helps minimize battery discharge when the PA is in standby mode. When VAPC is below the enable threshold voltage, the PA goes into a standby mode, which reduces battery current (ICC) to 6 A, typical, under nominal conditions. For voltages less than 700 mV at the APC input (pin 14), the PA bias is held at ground. As the APC input exceeds the enable threshold, the bias will activate. After an 8 s delay, the amplifier internal bias will ramp quickly to match the ramp voltage applied to the APC input. In order for the internal bias to precisely follow the APC ramping voltage, it is critical that a ramp pedestal is set to the APC input at or above the enable threshold level with a timing at least 8 s prior to ramp-up. This will be discussed in more detail in the following section, "Power Ramping Considerations for 3GPP Compliance".
Band Select
The Combinational Logic cell also includes a simple gate arrangement that selects the desired operational band by activating the appropriate current buffer. The voltage threshold level at the Band Select input (pin 16) will determine the active path of the bias output to the GaAs die.
Voltage Clamp
The Voltage Clamp circuit will limit the maximum bias voltage output applied to the bases of the HBT devices on the GaAs die. This provides protection against electrical overstress (EOS) of the active devices during high voltage and/or load mismatch conditions. Figure 8 shows the typical transfer function of the APC input to buffer output under resistively loaded conditions. Notice the enable function near 600 mV, and the clamp acting at 2.15 V, corresponding to a supply voltage of 4.0 V.
Figure 8. Base Bias Voltage vs. APC Input, VCC = 4.0 V
2.5
2.0
Base Bias (volts)
1.5
clamping occurs
1.0
0.5
0.0 0.0 0.5 1.0 1.5 APC input (volts) 2.0 2.5 3.0
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CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Technical Information
Due to output impedance effects, the bias of the GaAs devices increases as the supply voltage increases. The Voltage Clamp is designed to gradually decrease in level as the battery voltage increases. The performance of the clamp circuit is enhanced by the band gap reference that provides a supply-, process-, and temperature-independent reference voltage. The transfer function relative to VBAT is shown in Figure 9. For battery voltages below 3.4 V, the base bias voltage is limited by the common mode range of the buffer amplifier. For battery voltages above 3.4 V, the clamp limits the base bias.
Figure 9. Base Bias Clamp Voltage vs. Supply Voltage
2.6 2.5 clamp 2.4 Base Bias Clamp (Volts) 2.3 2.2 2.1 2.0 1.9 1.8 1.7 3.00 3.25 3.50 3.75 Vcc (Volts)
101749_013b
4.00
4.25
4.50
Current Buffer
The output buffer amplifier performs a vital function in the CMOS device by transferring the APC input voltage ramp to the base of the GaAs power devices. This allows the APC input to be a high impedance port, sinking only 10 A, typical, assuring no loading effects on the PAC circuit. The buffers are designed to source the high GaAs base currents required, while allowing a settling time of less than 8 s for a 1.5 V ramp.
Power Ramping Considerations for 3GPP Compliance
These are the primary variables in the power control loop that the system designer must control: * * * * * software control of the DSP / DAC software control of the transmitter timing signals ramp profile attributes - pedestal, number of steps, duration of steps layout of circuit / parasitics RC time constants within the PAC circuit design
All of these variables will directly influence the ability of a GSM transmitter power control loop to comply with 3GPP specifications.
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Technical Information
CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Although there is a specific time mask template in which the transmitter power is allowed to ramp up, the method is very critical. The 3GPP system specification for switching transients results in a requirement to limit the edge rate of output power transitions of the mobile. Switching transients are caused by the transition from minimum output power to the desired output power, and vice versa. The spectrum generated by this transition is due to the ramping waveform amplitude modulation imposed on the carrier. Sharper transitions tend to produce more spectral "splatter" than smooth transitions. If the transmit output power is ramped up too slowly, the radio will violate the time mask specification. In this condition, the radio may not successfully initiate or maintain a phone call. If the transmit output power is ramped up too quickly, this will cause RF "splatter" at certain frequency offsets from the carrier as dictated by the 3GPP specification. This splatter, known as Output RF Spectrum (ORFS) due to Switching Transients, will increase the system noise level, which may knock out other users on the system. The main difficulty with TDMA power control is allowing the transmitter to ramp the output power up and down gradually so switching transients are not compromised while meeting the time mask template at all output power levels in all operational bands. The transmitter has 28 s to ramp up power from an off state to the desired power level. The GSM transmitter power control loop generally involves feedback around the GaAs PA, which limits the bandwidth of signals that can be applied to the PA bias input. Since the PA is within the feedback loop, its own small-signal frequency response must exhibit a bandwidth 5 to 10 times that of the power control loop. As discussed in the previous section, the PA bias is held at ground for inputs less than 700mV. As the APC input exceeds the enable threshold, the bias will activate. After an 8 s delay, the amplifier internal bias will quickly ramp to match the ramp voltage applied to the VAPC input. Since the bias must be wide band relative to the power control loop, the ramp will exhibit a fast edge rate. If the APC input increases beyond 1V before the 8 s switching delay is allowed to occur after the bias is enabled, the PA will have significant RF output as the internal bias approaches the applied bias. During this ramp, the internal power control is running "open loop" and the edge rates are defined by the frequency response of the PA bias rather than that of the power control loop. This open loop condition will result in switching transients that are directly correlated to the PA bias bandwidth. Application of an initial APC voltage, which enables the bias at least 8 s before the VAPC voltage is ramped, will ensure that the internal bias of the PAM will directly follow the applied VAPC. As a result, the power control loop will define all edge transitions rather than the PA internal bandwidth defining the transition. Figures 10 and 11 show the relationship of the internal bias relative to the applied APC in two cases. One case has ramping starting from ground; the other case has ramping starting with an initial enable pedestal of 700 mV It is evident that the pedestal level is critical to . ensure a predictable and well behaved power control loop. To enable the CMOS driver in the PAM prior to ramp-up, a PAC output pedestal level to the APC input of the PAM (pin 14) should be set to about 700 mV. This pedestal level should have a duration of at least 8 s directly prior to the start of ramp up. Figure 12 shows typical signals and timings measured in a GSM transmitter power control loop. This particular example is at GSM Power Level 5, Channel 62. The oscilloscope traces are TxVCO_enable, PAC_enable, DAC Ramp, and VAPC (pin 14).
NOTE:
When the TxVCO is enabled, the pedestal becomes set at the APC input of the PAM, then the PAC is enabled, and finally the DAC ramp begins.
The device specifications for enable threshold level and switching delay are shown in Table 3.
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CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Figure 10. PAM Internal Bias Performance - No Pedestal Applied
Technical Information
1.6 1.4 1.2
Bias Voltage (V)
7 s
1.0 0.8 0.6 0.4 0.2 0.0 0.0 5.0 10.0 15.0
Time (s)
101749_013c
Enable threshold 550 mV
Vapc In (V) Internal bias (V)
20.0
25.0
30.0
35.0
Figure 11. PAM Internal Bias Performance - Pedestal Applied
1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.0 5.0 10.0 15.0 Time (s)
101749_013d
Bias Voltage (V)
Switching delay 7 s
Vapc In (V) Internal Bias (V) Enable threshold 550 mV
20.0
25.0
30.0
35.0
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Technical Information
CX77304-15
PA Module for Dual-Band GSM850 PCS1900 / GPRS Applications
Figure 12. GSM Transmitter - Typical Ramp-up Signals
T
1
DAC Ramp
2
TxVCO_enable
PAC_enable 3 VAPC 4 Ch1 Ch3 200 mV 1.00 V Ch2 Ch4
VAPC Pedestal
1.00 V 500 mV
BW M
10.0 s
A
Ch2
500 mV
100956_012
18
Skyworks Solutions, Inc.
Proprietary Information
101749A September 19, 2003
Ordering Information
Model Number CX77304-15 Manufacturing Part Number CX77304-15 Package 9.1 x 11.6 x 1.5 mm Operating Temperature -20 C to +100 C
Revision History
Revision A Level Date September 19, 2003 Initial Release Description
References
Application Note: Tape and Reel, Document Number 101568 Application Note: PCB Design and SMT Assembly/Rework, Document Number 101752 JEDEC Standard J-STD-020B
(c) 2001-2003, Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. ("Skyworks") products. These materials are provided by Skyworks as a service to its customers and may be used for informational purposes only. Skyworks assumes no responsibility for errors or omissions in these materials. Skyworks may make changes to its products, specifications and product descriptions at any time, without notice. Skyworks makes no commitment to update the information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from future changes to its products and product descriptions. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as may be provided in Skyworks' Terms and Conditions of Sale for such products, Skyworks assumes no liability whatsoever. THESE MATERIALS ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, RELATING TO SALE AND/OR USE OF SKYWORKSTM PRODUCTS INCLUDING WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. SKYWORKS FURTHER DOES NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM THE USE OF THESE MATERIALS. SkyworksTM products are not intended for use in medical, lifesaving or life-sustaining applications. Skyworks' customers using or selling SkyworksTM products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper use or sale. The following are trademarks of Skyworks Solutions, Inc.: SkyworksTM, the Skyworks symbol, and "Breakthrough Simplicity"TM. Product names or services listed in this publication are for identification purposes only, and may be trademarks of third parties. Thirdparty brands and names are the property of their respective owners. Additional information, posted at www.skyworksinc.com, is incorporated by reference.
General Information: Skyworks Solutions, Inc. 20 Sylvan Rd. Woburn, MA. 01801 www.skyworksinc.com

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