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Supports Dual-Band, Tri-Mode
Battery cell operation (2.7 V to 3.0 V)
Higher level of integration
I/Q differential outputs for baseband interfaces
On-chip 100 to 640 MHz VCOs
Low power operation: <60 mA
48-pin Land Grid Array (LGA) 7x7 mm package
The RF25K Application-Specific Integrated Circuit (ASIC) is a triple-mode, dual-
band receiver (Rx) in a Land Grid Array (LGA) package; intended for use in Code
Division Multiple Access (CDMA) portable phones in both the cellular and Personal
Communications System (PCS) bands. As a dual mode IC, it can be used either in
CDMA mode or Advanced Mobile Phone System (AMPS) mode.
The device incorporates all the components required to implement the complete
Dual-Band, Tri-Mode receiver front end; from the Low Noise Amplifier (LNA) to In-
Phase and Quadrature (I/Q) demodulator stages, except for filters and the PCS
LNA. In addition to the cellular band LNA, there are separate mixers for the AMPS,
CDMA 800 MHz, and PCS bands. The AMPS mixer output is single-ended,
followed by the external AMPS Intermediate Frequency (IF) Surface Acoustic Wave
(SAW) filter. The cellular and PCS mixers have balanced outputs for external IF
SAW filtering. The IF SAW filters are followed by a Variable Gain Amplifier (VGA)
and an I/Q demodulator.
The IF filter outputs are buffered at the input of the VGA, which are enabled
depending on the selected mode. The VGA has a dynamic range greater than 90
dB, and common stage for all modes.
There are two on-chip Very High Frequency (VHF) Voltage Control Oscillators
(VCO), which operate with external tank circuits to provide the Local Oscillator (LO)
signals for the I/Q demodulator.
The Noise Figure, Gain, and Third Order Input Intercept Point (IIP3) of each stage
in the receiver chip are optimized to meet the system requirements for AMPS and
CDMA modes as per TIA/EIA-98-B and ANSI J-STD-018 (PCS). Employing silicon
bipolar technology, the ASIC is designed for high performance with a high level
integration and a cost-effective RF solution for dual-band, tri-mode phone
application.
The device package and pinout are shown in Figure 1. A block diagram of the
RF25K is shown in Figure 2.
Applications
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Tri-mode phone
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In the cellular band:
鈥?AMPS
鈥?CDMA (US)
鈥?CDMA (Japan)
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In the PCS band:
鈥?PCS (US)
鈥?PCS (Korean)
Data Sheet
Premliminary 鈥?Conexant Systems, Inc.
Doc. No. 101249A
August 24, 2000
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