Motorola GP380 Series Información de servicio - Página 9

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1.0

Introduction

This chapter provides a detailed theory of operation for the radio RF circuits. Refer to the relevant

section of this manual for details of the operation of the Controller Circuits.

2.0

(Refer to Figure 2-1 and the Lowband Transmitter schematic diagram)

The Lowband transmitter consists of the following basic circuits :

Antenna switch/harmonic filter.

Antenna matching network.

Power Control Integrated Circuit (PCIC).

2.1

Power Amplifier (PA)

The power amplifier (PA) consists of two LDMOS devices:

PA driver IC, U101.

PA final stage, Q100.

The LDMOS driver (U101) provides 2-stage amplification using a supply voltage of 7.3V. The

amplifier is capable of supplying an output power of 0.3W (pins 6 and 7) with an input signal of 2mW

at (pin16). The current drain is typically 120mA while operating in the frequency range of

29.7 - 50 MHz. The power output of this stage is varied by the power control loop which controls the

voltage on pin 1.

SPI Bus

P C I C

V Control

Power Amplifier (PA)

PA Driver

Figure 2-1 Lowband Transmitter Block Diagram.

THEORY OF OPERATION

Antenna switch bias

Gate bias

Antenna Switch/

PA Final

Harmonic Filter

Stage

Chapter 2

Antenna

Matching

Network