User Guide

PAMS Technical Documentation 3. System Module

NSD-5

Issue 1 05/02 Nokia Corporation Page 45

Receiver

The following sections describe the Rx section chain from duplexer down to the I/Q sig-

nals for CDMA fed to the baseband.

Front End

In DCT3, the Stealth LNA and downconverter was used with an external bipolar LNA. In

Zim, the Alfred front end (N701) is used (same as that of Columbia). The 800MHz section

of Alfred IC is unused. It is critical that the LO must be present 5ms before Alfred is pow-

ered on. The software has been informed about this. This is a very linear part. Alfred is a

trimode dualband receiver front end (with 800MHz section not used). It houses LNAs and

downconverters (a combination of RFA, passive mixer, and IFA) for each band. The inter-

nal LO buffer provides the necessary gain to the UHF Rx LO to the level the mixer wants

to see. The mixer output feeds the IF filter single-ended. The LNAs have single-ended

inputs and outputs. External matching components are provided for both the LNA and

the mixer. The LNA is bypassable.

Table 14: PCS 1900MHz LNA Specs

Mode NF

IIP

Current

high gain 12dB 1.5dB 7dBm 5mA

LNA bypass -5dB 4dB 20dBm 0.1mA