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Only for training and service purposes
3. TECHNICAL BRIEF
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3.21 Power Amplifier Module
The SKY77344 Power Amplifier Module(PAM) is designed in a compact from fact for quad-band cellular
handsets comprising GSM850/900,DCS1800,PCS1900,supporting GMSK and linear EDGE modulation. Class12
General Packet Radio Service(GPRS) multi-slot operation is also supported.
The module consists of a GSM850/900 PA block and a DCS1800/PCS1900 PA block,impedance matching
circuitry for 50ohm input and output impedances, and a Multi-function Power Amplifier Control(MFC) block.
A custom CMOS integrated circuit provides the internal MFC function and interface circuitry.
Two separate Heterojunction Bipolar Transistor(HBT) PA blocks are fabricated onto InGaP die; one supports
the GSM850/900 bands, the other supports the DCS1800 and PCS1900 bands. Both PA blocks share common
power supply pins to distribute current. The InGaP die, the silicon die, nad the passive components are
mounted on a multi layer laminate substrate. The assembly is encapsulated with plastic overmold.
RF input and output ports are internally matched to 50ohm to reduce the number of external components
Extremely low leakage current(2.5uA) maximizes handset standby time. Band select(BS) circuitry select GSM
transmit frequency band(logic0) and DCS/PCS transmit frequency(logic1). MODE circuitry selects GMSK
modulation (logic0) or EDGE modulation(logic1). VRAMP controls the output power for GMSK modulation
and provides bias optimization for EDGE modulation depending on the state of MODE control.
The integrated multi-function(MFC) provides envelope amplitude control in GMSK mode, reducing
sensitivity to input drive, temp, power supply, and process variation. In EDGE mode, the MFC configures the
PA for fixed gain, and provides the ability to optimize the PA bias operation at different power levels, This
circuitry regulates PA bias conditions, reducing sensitivity to temp., power supply, and process variation. The
Enable input signal(pin8) provides a standby state to minimize battery drain..
.Table 9 PAM pin description
Pad
Name
Description
1
MODE
GMSK/EDGE Power control mode:
Low = GMSK. High = EDGE
2
DCS/PCS_IN
RF input(DCS/PCS bands) DC blocked
BS
Band select
4
VBIAS
Analog PA bais control (All bands, EDGD mode)
5
VBATT
DC supply
6
VRAMP
Analog output power control (All bands, GMSK mode)
7
GSM_IN
RF input (CEL/EGSM bands) DC blocked
8
EN
Transmit enable/ disable. Low = disable
9
GSM_OUT
RF output (CEL/EGSM bands) DC blocked
*12
RSVD2
Reserved
*16
DCS/PCS_OUT
RF output(DCS/PCS bands) DC blocked
*10, 11,
1~15
GND
Ground
Pad
GND PAD GRID
Ground pad grid is device underside
Содержание GT350
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