Panasonic EB-GD93, Техническое руководство

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RF OVERVIEW
MCUK001001G8 Section 3 Issue 1
Technical Guide – 9 – Revision 0
Figure 3.3: GSM 1800 Frequency Plan
3.2.2 General
The RF circuit design is built around an Hitachi Bright III GSM transceiver IC. Other major components include filters, power
amplifiers, VCOs and the antenna subsystems.
In either band, GSM 900 or GSM 1800, the Rx IF is fixed at 225 MHz and the 2nd IF at 45 MHz. Therefore, the 2nd local
oscillator is fixed at 540 MHz for receiver modes. This oscillator is also fixed at 540 MHz for transmit modes.
The Tx VCO is on-channel in both GSM 900 and GSM 1800 modes of operation.
3.2.3 Antenna
The antenna is a fixed helical type.
A mechanical switch is used to route the RF signal from the external antenna for handsfree operation and test purposes.
3.2.4 Transmit and Receive
The transmit and receive paths are covered in their own specific chapters later in this manual.
3.2.5 RF and Accessory Connector
An external antenna connector for use with handsfree accessories is located close to the PA module to minimise power loss.
Therefore, the PAs do not have to be driven so hard, allowing the voltage supply to be lower, thus improving battery
performance.
1805-1880 MHz
Rx RF LO
1580-1655 MHz
Tx RF LO
1575-1650 MHz
TX VCO
1710-1785 MHz
Fcomparison
135 MHz
Fdiff
135 MHz
Rx 1st IF
225 MHz
IF LO VCO
540 MHz
Rx 2nd IF
45 MHz
÷2
45 MHz
270 MHz
I
Q
I
Q
÷2
÷6
90 MHz
÷2
270 MHz
10215-1
135 MHz