Motorola HT Series

Table of Contents v
6.3.3 Automatic Gain Control Circuit.........................................................................6-7
6.4 Frequency Generation Circuitry....................................................................................6-8
6.5 Synthesizer ................................................................................................................... 6-9
6.6 Voltage-Controlled Oscillator (VCO)........................................................................... 6-10
Chapter 7 Low Band, 800 MHz, PassPort & 900 MHz
Theory of Operation...........................................................7-1
7.1 Introduction ...................................................................................................................7-1
7.2 Low Band Transmitter...................................................................................................7-1
7.2.1 Power Amplifier (PA)........................................................................................7-1
7.2.2 Antenna Switch................................................................................................7-2
7.2.3 Harmonic Filter.................................................................................................7-2
7.2.4 Antenna Matching Transformer .......................................................................7-2
7.2.5 Power Control Integrated Circuit (PCIC).......................................................... 7-2
7.2.6 Temperature Cut Back Circuit..........................................................................7-2
7.2.7 Electrostatic Discharge (ESD) Protection Circuit.............................................7-2
7.3 Low Band Receiver....................................................................................................... 7-3
7.3.1 Receiver Front-End..........................................................................................7-3
7.3.2 Receiver Back-End ..........................................................................................7-4
7.3.3 Automatic Gain Control (AGC).........................................................................7-4
7.3.4 Frequency Generation Circuit..........................................................................7-4
7.4 Synthesizer ................................................................................................................... 7-5
7.5 Voltage Control Oscillators (VCO) ................................................................................ 7-6
7.5.1 Receive VCO ...................................................................................................7-6
7.5.2 Transmit VCO ..................................................................................................7-6
7.5.3 Buffer ...............................................................................................................7-6
7.5.4 Diplexer/Output Filters .....................................................................................7-7
7.5.5 Prescalar Feedback.........................................................................................7-7
7.6 800 MHz Transmitter ....................................................................................................7-7
7.6.1 Power Amplifier................................................................................................7-7
7.6.2 Antenna Switch................................................................................................7-8
7.6.3 Harmonic Filter.................................................................................................7-8
7.6.4 Power Control Integrated Circuit (PCIC).......................................................... 7-8
7.7 800 MHz Receiver ........................................................................................................7-9
7.7.1 Receiver Front-End..........................................................................................7-9
7.7.2 Receiver Back-End ........................................................................................7-10
7.7.3 Automatic Gain Control Circuit.......................................................................7-10
7.7.4 Frequency Generation Circuit........................................................................7-11
7.8 Synthesizer .................................................................................................................7-12
7.8.1 Voltage Control Oscillator (VCO)...................................................................7-13
7.9 Trunked Radio Systems..............................................................................................7-14
7.9.1 Privacy Plus Trunked Systems ......................................................................7-14
7.9.2 LTR™ Trunked Systems................................................................................7-14
7.9.3 MPT Trunked Systems ..................................................................................7-14
7.9.4 PassPort™ Trunked Systems........................................................................7-15
7.9.4.1 Power Supplies..................................................................................... 7-15