CX74001
Rx ASIC for CDMA, AMPS, and PCS Applications
The CX74001 Application-Specific Integrated Circuit (ASIC) is a triple-mode, dual-
band receiver (Rx) intended for use in Code Division Multiple Access (CDMA)
portable phones in both cellular and Personal Communications System (PCS)
bands, as well as Advanced Mobile Phone System (AMPS) mode.
The device is a highly integrated super-heterodyne receiver. It incorporates all the
components required to implement the receiver chain, from the low-noise amplifier
(LNA) to the In-Phase and Quadrature (I/Q) demodulator stages, except for the
external Surface Acoustic Wave (SAW) filters and matching components. There
are two internal Low Noise Amplifiers (LNAs). The Cellular LNA has three-step gain
stages, and the PCS LNA gain has a bypass feature.
After RF signal amplification and filtering, the received signal is mixed down from
RF to the Intermediate Frequency (IF). There are separate mixers for AMPS,
CDMA, and PCS bands. The CDMA cellular and PCS mixers have balanced
outputs for the IF SAW filters, while the AMPS differential output can be combined
externally to mate to a single-ended SAW filter. After IF filtering, the IF signal is
amplified by a Variable Gain Amplifier (VGA) and fed to an I/Q demodulator
resulting in baseband I/Q signals at the output.
The VGA has a minimum dynamic range of 90 dB with a control voltage range from
0.5 to 2.5 Volts, and it is common to all modes. There are two VHF oscillators
which operates with external tank circuits to provide Local Oscillator (LO)
frequencies for the I/Q demodulator in the cellular and PCS bands.
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-C. Employing BiCMOS technology, the ASIC is
designed for low cost, high performance, and a high level of integration.
The device package and pinout are shown in Figure 1. A system block diagram of
the CX74001 is shown in Figure 2.
Distinguishing Features
•
Supports single and dual-band, and tri-mode
handsets
•
Battery cell operation (2.7 V < Vcc < 3.3 V)
•
Dual Low Noise Amplifiers (800 MHz / 1900 MHz)
•
PCS LNA With Bypass Feature
•
Three-Step Cellular LNA Gain
•
I/Q Interface
•
Dual 200-600 MHz VHF Oscillators
•
VCO On/Off control For Standby Current
Optimization
•
CDMA Single IF Feature
•
48-pin, 7 x 7 mm RF Land Grid Array (RFLGA™)
package with down-set paddle.
Applications
•
•
•
•
•
•
•
•
Cellular and PCS band phones
CDMA and AMPS modes in the cellular band
AMPS
CDMA-US
CDMA-Japan
CDMA mode in the PCS band
PCS-US
PCS-Korea
PCS_LNA_BIAS_RES
CELL_LNA_ OUT
NC
PCS_LNA_OUT
CELL_LNA_BIAS_RES
RF_BIAS_RES
CELL_MIX_IN
PCS_MIX_IN
PCSMIX_BYPASS
CELL_LO
PCS_LO
48
47
46
45
44
43
42
41
40
39
LNA_CTRL1
PCS_LNAIN
LNA_CTRL0
CELL_LNA_IN
VCC_RF_BIAS
CELL_LNA_EMIT
CELL/PCS
FM/CDMA
VCO_VCC
VCO_ON
CELL_TANK-
CELL_TANK+
PCS_TANK-
1
2
3
4
5
6
7
8
9
10
11
12
13
38
37
36
35
34
33
32
31
30
29
28
27
26
25
VCC_MIX
PCS_MIXER_OUT+
PCS_MIXER_OUT-
AMPS_MIX_OUT+
AMPS_MIX_OUT-
CDMA_MIX_OUT+
CDMA_MIX_OUT-
PCS_VGA_IN+
PCS_VGA_IN-
AMPS_VGA_IN
CDMA_VGA_IN+
CDMA_VGA_IN-
VCC_IF
14
15
16
PLL- 17
SIF 18
I- 19
I+ 20
Q+ 21
Q- 22
SLEEP 23
VGA_CONTROL 24
PCS_TANK+
LOD
PLL+
CNXT061
Figure 1. CX74001 Rx ASIC Pin-Out (Top View)
Data Sheet
Skyworks
Proprietary Information and Specifications are Subject to Change
Doc. No. 101134A
March 5, 2002
SKYWORKS [ SKYWORKS SOLUTIONS INC. ]
