The SKY77518-21 is a transmit and receive front-end module (FEM) with Integrated Power Amplifier Control
(iPAC) for dual-band cellular handsets comprising GSM900 and DCS1800 operation. Designed in a low
profile, compact form factor, the SKY77518-21 offers a complete Transmit VCO-to- Antenna and
Antenna-to-Receive SAW filter solution. The FEM also supports Class 12 General Packet Radio Service (GPRS)
multi-slot operation.
The module consists of a GSM900 PA block and a DCS1800 PA block, impedance-matching circuitry for 50
Ω input and output impedances, TX harmonics filtering, high linearity and low insertion loss PHEMT RF
switches, diplexer and a Power Amplifier Control (PAC) block with internal current sense resistor. A custom
BiCMOS integrated circuit provides the internal PAC function and decoder circuitry to control the RF switches.
The two Heterojunction Bipolar Transistor (HBT) PA blocks are fabricated onto a single Gallium Arsenide
(GaAs) die. One PA block supports the GSM900 band and the other PA block supports the DCS1800 band. Both
PA blocks share common power supply pads to distribute current. The output of each PA block and the outputs
to the two receive pads are connected to the antenna pad through PHEMT RF switches and a diplexer. The
GaAs die, PHEMT die, Silicon (Si) die and passive components are mounted on a multi-layer laminate substrate.
18
The assembly is encapsulated with plastic overmold. Band selection and control of transmit and receive modes
are performed using two external control pads. Refer to the functional block diagram in Figure.3-2-1below. The
band select pad (BS) selects between GSM and DCS modes of operation. The transmit enable (TX_EN) pad
controls receive or transmit mode of the respective RF switch (TX = logic 1). Proper timing between transmit
enable (TX_EN) and Analog Power Control (VRAMP) allows for high isolation between the antenna and
TXVCO while the VCO is being tuned prior to the transmit burst.
The SKY77518-21 is compatible with logic levels from 1.2 V to VCC for BS and TX_EN pads, depending on
the level applied to the VLOGIC pad. This feature provides additional flexibility for the designer in the selection
of FEM interface control logic.
3.2.2 GB100a/GB105a/GB101a/GB107a (SKY77517)
Figure.3-2-2 SKY77518 FUNCTIONAL BLOCK DIAGRAM
The SKY77517–21 is a transmit and receive front-end module (FEM) with Integrated Power Amplifier Control
(iPAC.) for dual-band cellular handsets comprising GSM850 and PCS1900 operation. Designed in a low profile,
compact form factor, the SKY77517–21 offers a complete Transmit VCO-to-Antenna and Antenna-to-Receive
SAW filter solution. The FEM also supports Class 12 General Packet Radio Service (GPRS) multi-slot
operation.
The module consists of a GSM850 PA block and a PCS1900 PA block, impedance-matching
circuitry for 50 Ω input and output impedances, TX harmonics filtering, high linearity and low insertion loss
PHEMT RF switches, diplexer and a Power Amplifier Control (PAC) block with internal current sense resistor.
19
A custom BiCMOS integrated circuit provides the internal PAC function and decoder circuitry to control the RF
switches. The two Heterojunction Bipolar Transistor (HBT) PA blocks are fabricated onto a single Gallium
Arsenide (GaAs) die. One PA block supports the GSM850 band and the other PA block supports the PCS1900
band. Both PA blocks share common power supply pads to distribute current. The output of each PA block
and the outputs to the two receive pads are connected to the antenna pad through PHEMT RF switches and a
diplexer. The GaAs die, PHEMT die, Silicon (Si) die and passive components are mounted on a multi-layer
laminate substrate. The assembly is encapsulated with plastic overmold.
Band selection and control of transmit and receive modes are performed using two external control pads. Refer
to the functional block diagram in Figure.3-2-2below. The band select pad (BS) selects between GSM and PCS
modes of operation. The transmit enable (TX_EN) pad controls receive or transmit mode of the respective RF
switch (TX = logic 1). Proper timing between transmit enable (TX_EN) and Analog Power Control (VRAMP)
allows for high isolation between the antenna and TX-VCO while the VCO is being tuned prior to the transmit
burst.
The SKY77517 is compatible with logic levels from 1.2 V to VCC for BS and TX_EN pads, depending on the
level applied to the VLOGIC pad. This feature provides additional flexibility for the designer in the selection of
FEM interface control logic.
20
26MHz Clock (DCXO)
Figure.3-3 Crystal Oscillator Functional Overview
The XO_TUNE register holds the digital correction value for the crystal oscillator frequency. The XOMODE
bits of XO_INIT1 register contain setup informations for the crystal oscillator (for example, current
programming, etc.).See Figure .3-3 Crystal Oscillator Functional Overview.
The registers XO_INIT2 and XO_INIT3 contain the coefficients information for the linearization unit of crystal
oscillator (LUXO) This linearization unit computes the required digital control word out of the programmed
AFC bits in order to have a linear pulling curve ppm vs. AFC word. The resulting digital control word DIG is
filtered by a digital lowpass filter, which can be scaled or deactivated using the bits DIGFILT0 and DIGFILT1
of the XO_INIT3 register.
The frequency correction splits into 2 parts:
1. The XOCAL bits in the XO_INIT1 register are used for the coarse frequency adjustment and are set once for
a mobile lifetime (during production test)
2. The XO_TUNE register contains the information for frequency correction when the mobile is used (correction
of temperature drift, crystal aging)
21
RTC(32.768KHz Crystal)
Figure.3-4 E-GoldVoice RTC Interface
22
3.5 LCD Interface(3 wire SPI interface)
Figure.3-5-1 LCD Interface
Figure.3-5-2 Charging PUMP Interface
23
24
3.6 SIM Card Interface
Figure.3-6 SIM CARD Interface
25
3.7 KEYPAD Interface
Figure.3-7 KEY MAXTRIX Interface
26
3.8 Battery Charging Block Interface
Figure.3-8 Charging IC Interface
27
3.9 RF Interface
Figure.3-9 RF Module/SAW Filter Interface
28
29
3.10 Audio Interface
Figure.3-10-1 Audio Interface
30
Loading...
+ 85 hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.