Transmitter - Nokia RH-27 Series Technical Documentation Manual

CCS Technical Documentation
Two VHF synthesizers consist of: RX VHF Synthesizer includes integrated PLL and VCO
and loop filter and resonator. The output of RX-VHF PLL is used as LO signal for the sec-
ond mixer in receiver. TX VHF Synthesizer and Loop filter is integrated into the RF ASIC.
See depicted block diagrams and synthesizer characteristics from Synthesizer specifica-
tion document.

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 180.54MHz.
The cellular band is 824.01-848.97MHz and PCS band is 1850.01-1909.95MHz.
Common IF
The RF modulator is integrated with Programmable Gain Amplifier (PGA) and IF output
buffer inside RFIC-chip. I- and Q-signals, that are output signals from BB-side SW IQ-
modulator, have some filtering inside the RF ASIC before RF modulation is performed.
The required LO-signal from TXVCO is buffered with phase shifting in the RF ASIC. After
modulation (p/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 50W 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 +6dBm linear output power. Mixer is inside RF IC. Note,
that in this point, term linear means -33dB ACP. The required LO power is about -6dBm.
The LO signal is fed from RF IC.
Before power amplifier RF signal is filter in band filter. The typical insertion loss is about
-2.7dB, and maximum less than -3.0dB. The input and output return losses are about
-10dB.
Power amplifier is 50W/50W 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 RF IC to be filtered in TX IF
strip filter, and after that back to RF IC, to the up-converter mixer. The LO-signal to the
mixer is buffered and balanced inside RF IC. The mixer output is enabled by TXP2 TX con-
trol signal. The maximum linear (balanced) RF signal level to 50W load is about +7dBm.
After RF IC 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 -5.0dB. This filter
hasrelatively 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.
Issue 1 11/2003
© 2003 Nokia Corporation
System Module
Confidential
RH-27
Page 29