RF25A-12 데이터 시트보기 (PDF) - Conexant Systems

부품명

상세내역

제조사

RF25A-12

RF25A for CDMA, and AMPS Applications

Conexant Systems 

RF25A

RF25A for CDMA, and AMPS Applications

The RF25A device includes the following functional blocks:

• Low Noise Amplifier (LNA)

• RF Downconverted Mixer

• Intermediate Frequency (IF) Variable Gain Amplifier (VGA)

• In-Phase and Quadrature (I/Q) Demodulator

• Voltage Controlled Oscillator (VCO)

The RF25A Application-Specific Integrated Circuit (ASIC) is a dual-mode, single-

band receiver (Rx) intended for use in Code Division Multiple Access (CDMA)

portable phones in the cellular band. It can be used in CDMA mode or Advanced

Mobile Phone System (AMPS) mode. The ASIC provides excellent RF

performance with low DC power dissipation and is assembled in a low cost, high

performance, 40-pin Land Grid Array (LGA) 6 x 6 mm package.

The device incorporates all the components required to implement the complete

dual-mode receiver front end; from the Low Noise Amplifier (LNA) to the In-Phase

and Quadrature (I/Q) demodulator stages, except for external SAW filters. The LNA

amplifies the incoming signal and outputs to an external SAW filter. After filtering,

the signal goes to the mixer for downconversion. The mixer output for the AMPS

mode is single-ended, followed by the external AMPS Intermediate Frequency (IF)

Surface Acoustic Wave (SAW) filter. The mixer output for the CDMA mode mixer

has balanced outputs for external IF SAW filtering. The IF SAW filters are followed

by a Variable Gain Amplifier (VGA) and and I/Q demodulator. The mode selection

is controlled by a mode control pin.

The IF filter outputs are buffered at the input of the VGA, which has a dynamic

range greater than 90 dB.

The on-chip Very High Frequency (VHF) Voltage Controlled Oscillators (VCO)

operates with an external tank circuit to provide the Local Oscillator (LO) signal for

the I/Q demodulator.

The Gain, Noise Figure (NF), and third order Input Intercept (IIP3) of each stage in

the receiver chip are optimized to meet the system requirements for AMPS and

CDMA modes according to the TIA/EIA 98-B standard. Employing silicon bipolar

technology, the ASIC is designed for high performance with a high level of

integration and provides a cost-effective RF solution for dual-mode phone

applications

The RF25A pin-out is shown in Figure 1, a functional block diagram is illustrated in

Figure 2, and a schematic diagram in Figure 3.

Features

• Dual-Mode Operation

• Battery operation 2.7 to 3.6 V

• High level of integration

• Differential I/Q outputs for baseband interfaces

• On-chip 100 to 600 MHz VCO

• Low DC consumption: < 60 mA

• 40-pin Land Grid Array (LGA) 6 x 6 mm package

Applications

• CDMA and AMPS handset in the cellular band:

− AMPS

− CDMA (US)

− CDMA (Japan)

NC 1

LNA_DECOUPLE 2

NC 3

LNA_IN 4

VCC_RFBIAS 5

BIAS_SET 6

FM/CDMA 7

VCC_VCO 8

GND 9

TANK- 10

TANK+ 11

31 NC

30 NC

29 AMPS_MIXEROUT

28 CDMA_MIXEROUT-

27 CDMA_MIXEROUT+

26 MIX_BYPASS

25 VGA_AMPS_IN

24 VGA_CDMA_IN-

23 VGA_CDMA_IN+

22 VCC_IF

21 VGA_CONTROL

C506

Figure 1. RF25A Rx ASIC Pin-out

40-Pin LGA Package

Data Sheet

Conexant – Preliminary

Proprietary Information

Doc. No. 101110A

August 4, 2000

Share Link: