Functional Description - Panasonic EB-G60 Service Manual

GSM 1900
Uplink frequencies for the GSM 1900 band (512 = ARFCN = 810) can be calculated as follows:
Uplink frequency = 1930 MHz + ((ARFCN - 511) x 0.2 MHz) e.g. for CH680
1930 MHz + ((185 - 511) x 0. 2MHz)
= 1930 MHz + (33.8 MHz)
= 1963.8 MHz

5.3.3. Functional Description

DCOC
Ö . Ö
Rxin
Rxip
DCOC
Rxqn
Rxqp
PCO1
UHF-VCO
PCO2
(LO)
TXENA
RXENA
SXENA
Rxin
Rxip
Rxqn
Transceiver
CX74017
Rxqp
The main building block, illustrating as Fig 5.1 receive path, for the Dual Band receiver is the CX74017 transceiver IC
(U100) which includes a direct conversion receiver with I and Q quadrature demodulation. Received signals from the
antenna are passed to the dual band antenna switch module U111. This module contains a diplexer which filters the
signal to the required receiver path (E-GSM 900 or GSM 1800). Pin diode switches within U111 route the signal path
from the transmitter or to the receiver as required. Output signals from U111 are then applied via the dual band SAW
filter FL101 to the balanced Low Noise Amplifiers (LNA) onboard U100.Output from the LNAs are applied to the buffer
amplifiers and a pair of Gilbert Cell mixers within U100. The mixers convert the incoming signals directly down to
baseband frequencies. The I, Q local oscillator signals for the mixers is derived from a 925M-1880M Hz RFLO, dived
down by high speed converter. The receiver has two separate front-end blocks, optimized for 900 MHz and 1800 MHz
respectively.
The front-end gain is programmed as follows:
These settings allow the signal in the receiver to be optimized, particularly under high signal level conditions. Front-End
gain is programmed by 3-wire bus signal from the baseband.
The mixer stage is followed by the I, Q baseband low-pass filters and programmable gain amplifiers (PGA). Each three-
stage VGA is DC-coupled and has a 100 dB control range in 2 dB steps.
Rx-VCO
U106
VCTCXO
Fref
13MHz
AFC
LE
CLK
Data
U100
Fig 5.4. : Receiving Blocking
GSM
SAW
Dual-band
TR switch
DCS
SAW
F101 SAW Filter
VC1 VC2 VC3
– 5–11 –
ANT
U111