User Guide

RM-11
System Module CC Technical Documentation
Page 30 ©2004 Nokia Corporation Confidential Issue 1 02/2004
For proper AMPS-mode receiver (duplex) sensitivity, the IF signal is filtered in a
strip-filter before up-conversion. The upconverter mixer is actually a mixer with a LO and
output driver that is able to deliver about +6dBm linear output power. The mixer is inside
the RF IC. Note that in this point, the term “linear” means -33dB ACP. The required LO
power is about -6dBm. The LO signal is fed from the RF IC.
Before power amplifier RF signal is filter in band filter. The typical insertion loss is about
-2.7dB, and the maximum is less than -3.0dB. The input and output return losses are
about -10dB.
The power amplifier is a 50W/50W 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 +31dB and the linear output power is +30dBm (typical condi-
tion) with -28dB ACP. The nominal efficiency is 50%.
PCS Band
When operating in the PCS band, the IF signal is routed outside from RF IC to be filtered
in the TX IF strip filter, and after that back to the RF IC, then to the upconverter mixer.
The LO signal to the mixer is buffered and balanced inside the RF IC. The mixer output is
enabled by the TXP2 TX control signal. The maximum linear (balanced) RF signal level to
50 W load is about +7dBm.
Next, the RF IC-balanced RF signal is single-ended in 1:1 balun and then filtered in the
SAW filter. The typical insertion loss is about -4.0dB, and the maximum is less than
-5.0dB. This filter has a relatively high pass band ripple about 1.0-1.5dB with the largest
insertion being at the high end of the band. The input and return losses are about -10dB.
The power amplifier is a 50W/50W 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 +31 to +36dB and linear output power is +30dBm (typical condition)
with -28dB ACP. The nominal efficiency is 40%.
Power Control
For power monitoring, there is a power detector module (PDM) build up from a dual
coupler, a biased diode detector, and an NTC resistor. RF signals from both bands are
routed via this PDM. The RF isolation between couplers is sufficient not to lose filtering
performance given by duplex filters.
The diode output and NTC voltages are routed to the BB A/D converters for power
control. The TX AGC SW takes samples from the diode output voltage and compares that
value to the target value, and then adjusts the BB I-and Q-signal amplitude and/or RF IC
PGA settings to keep power control in balance.
NTC voltage is used for diode temperature compensation and for thermal shut down
when the radio board's temperature exceeds +85°C.
A false TX indication is based on the detected power measurement when the carrier is
not on.