Private Communication Systems
Mobile Phones
5.2 Hardware Description
The handset consists of five major integrated circuits:
1) HiGOLD (PMB 2800)
This IC is a combination of microprocessor and signalprocessor.
The microprocessor is responsible for controlling the keyboard, SIM-Card, EEPROM,
Flash and RAM. Furthermore it controls the power up/power down of the RF module
and sets the amplification of the PA.
The signal processor is responsible for processing the Rx I/Q signals (filtering,
equalizing, speech and channel decoding).
Furthermore it does the speech and channel encoding and the GSMK modulation of
the Tx I/Q signals.
3) GAIM (PMB 2905)
The GAIM provides the interface between the analogue signals (I/Q, voiceband, PA-
control) and its digital representation.
4) Receiver Circuit (PMB 2409)
This circuit provides the following main functionalities:
a) Low Noise Amplifier (LNA) with a fixed amplification of +20dB to amplify the input
RF signal.
b) Mixer to mix down the RF signal to the Intermediate Frequency (IF)
c) Programmable IF amplifier with a dynamic range of 60dB ( -10dB ... +50dB in
steps of 2dB)
d) Mixer to mix down the IF signal to the baseband, generating and inphase (I) and a
quadrature (Q) signal.
e) Offset compensation for the I/Q signals.
5) Transmitter Circuit PMB 2240/45
This circuit provides the IF synthesizer, the I/Q modulator, prescalers to regulate the
RF synthesizer and a buffer stage to feed the PA.
The antenna switch is mechanical, located in the Molex connector.
5.3 Power Supply Concept
Service Manual C1x V 1.0 PN MP ST
R. Fleuren
Sm_C1x_lvl2_v10_w97.doc Page 14 of 23 09/98
