User Guide

Nokia Customer Care System Module
Company Confidential RH-21
Issue 2 07/2004  2004 Nokia Corporation. Page 45
common 2GHz UHFVCO module is used for operation on both low and highband. A fre-
quency divider is integrated in the Safari.
Two VHF synthesizers consist of: RX VHF Synthesizer includes integrated PLL and VCO
and external loop filter and resonator. The output of RX-VHF PLL is used as LO signal for
the second mixer in receiver. TX VHF Synthesizer includes integrated PLL and external
amplifier, loop filter, and resonator. The output of TX-VHF PLL is used as a LO signal for
the IQ-modulator of the transmitter.
Transmitter
The transmitter RF architecture is an up-conversion type (desired RF spectrum is low side
injection) with (RF-) modulation and gain control at IF. The IF frequency is band related—
180.54 MHz in the cellular band and 181.80MHz in the PCS band. The cellular band is
from 824.01-848.97 MHz and the PCS band is from 1850.01-1909.95 MHz.
Common IF
The RF-modulator is integrated with a PGA (Programmable Gain Amplifier) and IF output
buffer inside the SAFARI_T RFIC-chip (I- and Q-signals that are output signals from BB-
side SW IQ-modulator have some filtering inside Safari before RF-modulation is per-
formed). The required LO-signal from the TXVCO is buffered with phase shifting in Safari.
After modulation (π/4 DQPSK or FM), the modulated IF signal is amplified in the PGA.
Cellular Band
When operating in cellular band, the IF signal is buffered at IF output stage that is
enabled by TXP1 TX control. The maximum linear (balanced) IF signal level to 50Ω load is
about –8 dBm.
For proper AMPS-mode receiver (duplex) sensitivity, IF signal is filtered in strip-filter
before up-conversion. The upconverter mixer is actually a mixer with LO and output
driver being able to deliver about +6 dBm linear output power. Note that in this point,
term linear means –33 dB ACP. The required LO power is about –6 dBm. The LO signal is
fed from Safari.
Prior to the power amplifier, the RF signal is filtered in a band-pass filter. The typical
insertion loss is about –2.7 dB, and maximum less than –3.5 dB. The input and output
return losses are approximately -10 dB.
The power amplifier is 50Ω/50Ω module. It does not have its own enable/disable control
signal, but it can be enabled by bias voltage and reference bias current signals. The gain
window is +27 to +31 dB and the linear output power is +30dBm (typical condition)
with –28 dB ACP. The nominal efficiency is 50 percent.
PCS Band
During operation in the PCS band, the IF signal is routed from the Safari to be filtered in
the TX IF SAW filter. The signal is returned to the Safari, and then routed to the up-con-
verter mixer. The LO-signal to the mixer is buffered and balanced inside the Safari. The
mixer output is enabled by the TXP2 TX control signal. The maximum linear (balanced) RF
signal level to a 50Ω load is about +7 dBm.