Chapter 5 Uhf Band 2 Theory Of Operation; Transmitter; General; Power Amplifier - Motorola HT Series Service Manual

UHF Band 2 Theory of Operation: Transmitter

Chapter 5 UHF Band 2 Theory of Operation

5.1

Transmitter

From VCO
5.1.1

General

(Refer to Figure
The UHF transmitter contains five basic circuits:

• power amplifier

• antenna switch
• harmonic filter
• antenna matching network
• power control integrated circuit (PCIC)
5.1.2 Power Amplifier
The power amplifier consists of two devices:
• 9Z67 LDMOS driver IC (U101)
• PRF1507 LDMOS PA (Q110)
The 9Z67 LDMOS driver IC contains a 2 stage amplification with a supply voltage of 7.3 V.
This RF power amplifier is capable of supplying an output power of 0.3 W (pin 6 and 7) with an input
signal of 2 mW (3 dBm) (pin16). The current drain would typically be 160 mA while operating in the
frequency range of 450-527 MHz.
The PRF1507 LDMOS PA is capable of supplying an output power of 7 W with an input signal of 0.3
W. The current drain would typically be 1300 mA while operating in the frequency range of 450-527
MHz. The power output can be varied by changing the biasing voltage.
P C I C
Vcontrol
P A
Driver

Figure 5-1. Transmitter Block Diagram

5-1)
Vcontrol
Antenna Switch/
PA-Final
Harmonic Filter/
Stage
Matching Network
Antenna
Jack
5-1