Siemens M35 Series Service Manual page 18

This circuit provides the following main functions:
•
Control of switch on of the Mobile phone by ON/OFF button, Ext Power (Charger) or real
time clock.
•
Watchdog monitor – switch off the mobile phone if no proper Watchdog signal send from
HiGOLD IC.
•
Voltage supply to the logic circuits – 2.90V, 2.65V & 1.92V, Simcard & real time clock in
HiGOLD IC.
•
Switch on the linear regulator to supply the 2.8V for the13Mhz Oscillator circuit.
•
RESET signal for the logic circuit.
•
Charge control signal for switching the charge FET.
•
Low battery detector.
•
Over voltage protection.
5) Receiver Circuit – Bright II HD155124F
This circuit provides the following main functions:
•
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).
•
Mixer to mix down the IF signal to the baseband, generating and inphase (I) and a
quadrature (Q) signal and feed the GAIM IC base-band signal, RX I/Q for the decoding
of the digital signal for the HiGOLD IC.
6) Transmitter Circuit – Bright II HD155124F
The GAIM IC generate the MOD I/Q base-band signal under the control of the HiGOLD IC
and feed the IQ modulator of the Bright II IC. The Bright II IC provides the IF synthesizer,
the I/Q modulator, prescaler to regulate the dual-band TX-VCO and feed the modulated GSM
signal to the PA.

The telephone support only 1.8V and 3V SIM card
For user with 5V SIM card, he need to upgrade the SIM card
through his service provider/network operator