Hardware Description - Siemens C25 Service Manual

5.2

Hardware Description

The handset consists of the following major integrated circuits:
1) HiGOLD (PMB 2800)
This IC is a combination of microprocessor and signalprocessor.
The microprocessor part of this component is responsible for controlling the
keyboard, SIM-Card, 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 part of PMB 2800 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.
2) GOLD-SX (PMB 2709)
The coprocessor PMB 2709 is used to realize advanced features regarding coding
of the speech signal. These are:
• Halfrate-Encoding
• Halfrate-Decoding
• Enhanced Fullrate Encoding
• Enhanced Fullrate Decoding
• Voice Activity Detection
• Comfort Noise
3) GAIM (PMB 2905)
The GAIM (GAIM = GSM Analog Interfacing Module) provides the interface between
the analogue signals (I/Q, voiceband, PA-control, charging control signals) and its
digital representation.
4) Receiver Circuit (PMB 2411)
This circuit provides the following main functionalities:
• Low Noise Amplifier (LNA) with a fixed amplification of +20dB to amplify
the input RF signal.
• Mixer to mix down the RF signal to the Intermediate Frequency (IF)
• Programmable IF amplifier with a dynamic range of 60dB ( -10dB ...
+50dB in steps of 2dB).
Service Manual C25 / C2588
Sm_C25_lvl2_v10_w97
Private Communication Systems
V 1.0
Page 17 of 32
Mobile Phones
ICP CD ST
R. Fleuren
02/99