CCS Technical Documentation
System Module
RH-41
Issue 2 09/2003
Nokia Corporation Confidential
Page 49
specification document [6].
Transmitter
The transmitter RF architecture is up-conversion type (desired RF spectrum is low side
injection) with (RF) modulation and gain control at IF. The IF frequency is band-related
being 180.54 MHz at cellular band and 181.80 MHz at PCS band. The cellular band is
824.01 MHz - 848.97 MHz and PCS band is 1850.01MHz -1909.95MHz.
Common IF
The RF modulator is integrated with Programmable Gain Amplifier (PGA) and IF output
buffer inside Taco_T RFIC-chip. I- and Q-signals, that are output signals from BB-side
SW IQ-modulator, have some filtering inside Taco before RF modulation is performed.
The required LO-signal from TXVCO is buffered with phase sifting in Taco. After modula-
tion (
π
/4 DQPSK or FM), the modulated IF signal is amplified in PGA.
Cellular Band
At operation 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 50
Ω
load is about
-8 dBm.
For proper AMPS mode receiver (duplex) sensitivity, IF signal is filtered in strip filter
before up-conversion. The up-converter mixer is actually a mixer with LO and output
driver being able to deliver about +6dBm linear output power. Note, that in this point,
term linear means –33dB ACP. The required LO power is about –6dBm. The LO signal is
fed from Taco.
Before power amplifier RF signal is filter in band filter. The typical insertion loss is about
–2.7dB, and maximum less than –3.5dB. Input and output return losses are about –10dB.
Power amplifier is 50
Ω
/50
Ω
module. It does not have 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 linear output power is +30dBm (typical condition) with –28dB ACP.
The nominal efficiency is 50%.
PCS Band
At operation in PCS band, the IF signal is routed outside from Taco to be filtered in TX IF
SAW filter, and after that back to Taco, to the up-converter mixer. The LO signal to the
mixer is buffered and balanced inside Taco. The mixer output is enabled by TXP2 TX con-
trol signal. The maximum linear (balanced) RF signal level to 50
Ω
load is about +7dBm.
After Taco-balanced RF signal is single-ended in 1:1 balun and then filtered in SAW fil-
ter. The typical insertion loss is about –4.0dB, and maximum less than –5.7dB. This filter
has relatively high pass band ripple (about 1.0-1.5dB), largest insertion being at high end
of the band. The input and return losses are about –10dB.
Power amplifier is 50
Ω
/50
Ω
module. It does not have own enable/disable control signal,
but it can be enabled by bias voltage and reference bias current signals. The gain window
