wireless
communications
products
Silicon Germanium CDMA
Transmit/Dual PLL RFlC
CX74002
Conexant Delivers RF Chipsets
for 2G and 3G CDMA Applications
The CX74002 device offers the highest level of integration a tri-
mode, dual-band CDMA transmit RFIC. The device is designed to
meet the needs of both 2G and 3G CDMA systems. Specifically
targeting the cdmaOne, cdma2000, and AMPS markets in the U.S.
and Korean cellular, Japan cellular, Korean PCS and U.S. PCS bands.
The CX74002 is also designed to be suitable for wideband CDMA
(WCDMA) applications in the IMT-2000 band. The device is built
using Conexant鈥檚 advanced silicon germanium (SiGe) bipolar
complementary metal oxide semiconductor (BiCMOS) process
technology. This process results in best-in-class current consumption
performance, hence increasing cellular phone talk time.
The CX74002 is a highly integrated super-heterodyne transmitter
(Tx) that incorporates all the active functional blocks up to the antenna:
an In-phase and Quadrature (I/Q) modulator that accepts the analog
I and Q outputs from the baseband analog processor and converts
them to intermediate frequency (IF) signals; a voltage controlled
oscillator (VCO) and very high-frequency (VHF) synthesizer to generate
the local oscillator (LO) signal for the quadrature demodulators for the
cellular and PCS bands; a UHF synthesizer to control the UHF oscilla-
tor; and a variable gain amplifier (VGA), which is required in CDMA
systems to provide linear variable output power at the antenna.
Distinguishing Features
鈥?Best-in-class current consumption
鈥?Tri-mode, dual-band functionality
鈥?I /Q to RF integration
鈥?Image-reject mixer
鈥?Three battery-cell operation (2.7V < VCC < 3.6V)
鈥?Split-band PCS drivers to improve Rx Band
noise performance
鈥?Tx power control with 90 dB dynamic range
鈥?Variable-gain RF block to meet in-band signal-
to -noise ratio (SNR)
鈥?6mm x 6mm land grid array (LGA)
chipscale package
The output of the VGA is fed to the image reject mixer. The output
of the image reject mixer is fed directly to the PA pre-driver without
the need for external SAW filters, resulting in a reduction of overall
cellular phone bill-of-material cost.
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