V1.0 Page 13 of 38 ICM MP CC ST
A35-A36-A40 Company Confidential 09/01
4.4.2 Receiver : Mixer, IF Amplifier and Demodulator
The symmetrical LNA amplified EGSM900 and GSM1800 signals arrive at the Notes
SMARTI pins 31,32,34,35, to be mixed down to the IF frequency of 360MHz..
To do so, the LO1 is guided via the SMARTI pins 22,23 to the different mixers.
Frequency calculation of the LO1: (Freq.GSM = RF+IF and Freq.PCN = RF-IF)
After mixing, the IF is filtered by an external SAW-Filter (Z500) to arrive again at the
SMARTI (input of the PGC-Amplifier).
The programmable PGC-Amplifier ensures an equalized level of the IF-Signal at the
input of the I/Q demodulator. To perform this, the PGC-Amplifier is switched
in 2 dB steps using the EGOLD+ signals (SYNSTR;SYGCDT;SYGCCL).
The demodulation is realised by the I/Q demodulator. To mix out the IF, the
2
nd
local oscillator frequency (1440MHz) divided by 4, is used.
Finally the “I” and “Q” signals are amplified and ready for further operations
through the GAIM part of the EGOLD+ (A/D conversion) as RX_I,RX_IX-RX_Q,RX_QX
at the SMARTI pins 1,3,4,48
The required voltage VCC2_8 is provided by N430
to
baseband
from LNA
To Next Page
Loading...
