User Guide

PAMS Technical Documentation 3. System Module
NSD-5
Issue 1 05/02 Nokia Corporation Page 43
Maximum Ratings
The maximum battery voltage during the transmission should not exceed 4.5V. Higher
battery voltages may destroy the power amplifier and other circuitry. The minimum bat-
tery voltage is 3.2V.
RF Connector
If nothing is plugged into the phone, the RF is connected to the single band antenna.
When the RF connection is made, the RF path is switched mechanically from the antenna
to the cable plugged in. Note: the RF connector is designed for RF tuning in the factory;
it is fragile and could be pulled off easily, destroying the PWB if care is not taken.
Single Band Internal Antenna
A single band 1900MHz internal antenna has been developed for the U.S. PCS band.
Antenna gain is 2-3dBi across the band. The transmitter output power is tuned to
23.2dBm to 23.5dBm at the RF connector.
Transmitter
The following sections describe the PCS transmitters working from the baseband signals
to the duplexers.
Duplexer
The front of the duplexer is covered with a shield. It is crucial that this shield is well sol-
dered down to avoid rejection problems. Solder joints along the mono block front (i.e.,
shield side) also are critical for rejection, while solder joints at the rear of the duplexer
serve only for mechanical securing. Due to the problem of silver leaching, the corners of
the duplexer should NOT be soldered. Only flat sections of the part should be soldered.
Table 12: Typical performance of the Scorpion duplexer
Power Amplifiers Module 1900MHz
The power amplifier is a GaAs HBT device. The PCS PA is reference designator N604. This
is a two-stage device with interstage matching; it does not require an external output or
input match. It is packaged in a standard module plastic package with a heat sink slug
underneath. The metal slug on the underside, which serves primarily as a heat sink, also
serves as a RF ground connection. A grid of vias is present under the slug to help conduct
heat into the PCB. All layers have a maximum amount of copper under the PAs to assist
with heat dissipation.
The PA is connected directly to Vbatt. The PA is switched on and off by controlling its
Parameter Transmitter Port Receiver Port
Insertion loss 3.3dB 3.7dB
Ripple (slope) 2.7dB 2.7dB
1850 - 1910MHz rejection 48dB
1930- 1990MHz rejection 44dB