UP MIXER Theory:A11
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BOARD - P6.0
RFT3100 Overview
The RFT3100 Baseband-to-RF Transmit Processor performs all transmit (Tx) signal processing
functions required between digital baseband and the Power Amplifier (PA) for IS-95 CDMA Cellular,
JSTD-018 PCS, and ARIB-53 (Japan) single band and dual band applications. The RFT3100
incorporates the previous-generation functionality of the IFT3000 Baseband-to-IF Processor togethe
with the RF up conversion and driver amplifiers. The RFT3100 offers the most advanced and integrated
CDMA Tx solution providing a board area savings of more than 65% over previous generation chipsets,
along with minimized power consumption for extended talk-time performance. The RFT3100 is available
in three configurations: Dual-band Cellular and PCS (RFT3100-1), Cellular-only (RFT3100-2), and PCS
only (RFT3100-3).
The RFT3100 connects directly with QUALCOMMs MSM5100 utilizing an analog baseband
interface. The baseband quadrature signals are up converted to the Cellular or PCS frequency bands
and amplified to provide signal drive capability to the PA. The RFT3100 includes an IF mixer for up
converting analog baseband to IF, a programmable PLL for generating Tx IF frequency, single sideband
up conversion from IF to RF, two Cellular and two PCS driver amplifiers, and Tx power control through
an 85 dB VGA. As added benefit, the single sideband up conversion eliminates the need for a band
pass filter normally required between the up converter and driver amplifier providing overall board area
and cost savings. RFT3100 functionality is specifically controlled from the MSM5105 via the three-line
serial bus interface (SBI).
Designed to meet the requirements for global CDMA markets, the RFT3100 will operate over the
following Tx frequency ranges:
Cellular band 824 MHz 925 MHz
PCS band 1750 MHz 1910 MHz
Range of supply voltage is from 2.7 V to 3.3 V, which provides operating compatibility for platform
utilizing a single-cell Li-Ion battery design. RFT3100 operating modes are controlled by the MSM5100
and include selective power-down, gain control, and punctured CDMA transmission (gated Tx power),
for optimal power savings and talk-time improvement. The RFT3100 is fabricated on an advanced
BiCMOS process, which accommodates both precision high-frequency analog circuits and low-powe
CMOS functions, and is provided in a 32-pad BCC++ plastic package.
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