Nokia Mobile Phones NSE-5 Series Service Manual page 65

PAMS
Technical Documentation
RF Module
The RF module converts the signal received by the antenna to a
baseband signal and vice versa.
It consists of a conventional superheterodyne receiver and a transmitter
for each band and also two frequency synthesizers for the required
mixing.
The architecture contains two integrated circuits, a CRFU3_D1 and a
SUMMA. They are both BiCMOS ASICs, which is a suitable technology for
integration of RF functions.
The CFRU3 includes:
– A LNA for each band with a step AGC
– Down converters for the receiver
– Image rejection upconversion mixers for the transmitter
– A prescaler for the 2 UHF VCO
The SUMMA includes:
– An AGC amplifier for the receiver
– A receiver mixer for the 13 MHz down conversion
– PLLs for the UHF and VHF synthesizers
– IQ–modulators for the transmitter
– A power control circuit for the transmitter
The power amplifiers (PAs) are MMIC technology (Monolithic Microwave
Integrated Circuit). They include three amplifier stages with input,
interstage and output matching.
On the next page is a graphical presentation of the used Frequency Plan.
Issue 1 07/99
NSE–5
System Module
Page 2 – 51