CommunicationCommunicationElectronicsElectronics

Principles amp ApplicationsPrinciples amp ApplicationsThird EditionThird Edition

Chapter 6Radio Transmitters

copy2001 GlencoeMcGraw-Hill

Louis E Frenzel

TRANSMITTER COMPONENTS

bull Carrier signal source usually a crystal oscillator or a frequency synthesizer

bull Multiple RF amplifiers to increase power level

bull High power final amplifier

bull Impedance matching circuits to ensure maximum power transfer

bull Modulator

Carrieroscillator

Audioamplifier

Driver

AM TRANSMITTER WITHHIGH-LEVEL MODULATION

Speechprocessing

Final poweramplifier

Buffer

DriverModulation

amplifier

Sidebandfilter

Microphone

Audioamplifier

Linear driver amplifier

AntennaTYPICAL SSB TRANSMITTER

Balancedmodulator

Speechprocessing

Carrieroscillator

Linear poweramplifier

LO

MixerBuffer Tunedcircuit

Phasemodulator

Microphone

Audioamplifier

Driver

TYPICAL FM TRANSMITTERUSING INDIRECT FM

Speechprocessing

Carrieroscillator

Final poweramplifier

Buffer Frequency multipliers

CLASSES OF AMPLIFIERS

bull Class A

ndash Conducts continuously

ndash Linear lowest distortion

ndash Least efficient (lt50)

bull Class B

ndash Conducts for 180ordm of input

ndash More efficient than class A

ndash Push pull circuit reduces distortion

CLASSES OF AMPLIFIERS (continued)

bull Class Cndash Conducts for less than 180ordmndash Highly efficientndash Generates distortion and harmonics

bull Class D and Endash Switching amplifiersndash Introduce distortion and harmonicsndash Most efficient (gt90)ndash Use BJT and enhancement mode

MOSFETS

Class A Operation

Class B Operation

+50 V

3 nF

047 F

10 H

410pF

20

20

300 pF

27 nH

27 nH

3 nF

3 nF

20 nH

20 nH

01 F

161

91

MRF 154

MRF 154

1 KW PUSH-PULL RF POWER AMPLIFIER

RFin

RFout

Note gate bias circuits not shown

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

TRANSMITTER COMPONENTS

bull Carrier signal source usually a crystal oscillator or a frequency synthesizer

bull Multiple RF amplifiers to increase power level

bull High power final amplifier

bull Impedance matching circuits to ensure maximum power transfer

bull Modulator

Carrieroscillator

Audioamplifier

Driver

AM TRANSMITTER WITHHIGH-LEVEL MODULATION

Speechprocessing

Final poweramplifier

Buffer

DriverModulation

amplifier

Sidebandfilter

Microphone

Audioamplifier

Linear driver amplifier

AntennaTYPICAL SSB TRANSMITTER

Balancedmodulator

Speechprocessing

Carrieroscillator

Linear poweramplifier

LO

MixerBuffer Tunedcircuit

Phasemodulator

Microphone

Audioamplifier

Driver

TYPICAL FM TRANSMITTERUSING INDIRECT FM

Speechprocessing

Carrieroscillator

Final poweramplifier

Buffer Frequency multipliers

CLASSES OF AMPLIFIERS

bull Class A

ndash Conducts continuously

ndash Linear lowest distortion

ndash Least efficient (lt50)

bull Class B

ndash Conducts for 180ordm of input

ndash More efficient than class A

ndash Push pull circuit reduces distortion

CLASSES OF AMPLIFIERS (continued)

bull Class Cndash Conducts for less than 180ordmndash Highly efficientndash Generates distortion and harmonics

bull Class D and Endash Switching amplifiersndash Introduce distortion and harmonicsndash Most efficient (gt90)ndash Use BJT and enhancement mode

MOSFETS

Class A Operation

Class B Operation

+50 V

3 nF

047 F

10 H

410pF

20

20

300 pF

27 nH

27 nH

3 nF

3 nF

20 nH

20 nH

01 F

161

91

MRF 154

MRF 154

1 KW PUSH-PULL RF POWER AMPLIFIER

RFin

RFout

Note gate bias circuits not shown

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

Carrieroscillator

Audioamplifier

Driver

AM TRANSMITTER WITHHIGH-LEVEL MODULATION

Speechprocessing

Final poweramplifier

Buffer

DriverModulation

amplifier

Sidebandfilter

Microphone

Audioamplifier

Linear driver amplifier

AntennaTYPICAL SSB TRANSMITTER

Balancedmodulator

Speechprocessing

Carrieroscillator

Linear poweramplifier

LO

MixerBuffer Tunedcircuit

Phasemodulator

Microphone

Audioamplifier

Driver

TYPICAL FM TRANSMITTERUSING INDIRECT FM

Speechprocessing

Carrieroscillator

Final poweramplifier

Buffer Frequency multipliers

CLASSES OF AMPLIFIERS

bull Class A

ndash Conducts continuously

ndash Linear lowest distortion

ndash Least efficient (lt50)

bull Class B

ndash Conducts for 180ordm of input

ndash More efficient than class A

ndash Push pull circuit reduces distortion

CLASSES OF AMPLIFIERS (continued)

bull Class Cndash Conducts for less than 180ordmndash Highly efficientndash Generates distortion and harmonics

bull Class D and Endash Switching amplifiersndash Introduce distortion and harmonicsndash Most efficient (gt90)ndash Use BJT and enhancement mode

MOSFETS

Class A Operation

Class B Operation

+50 V

3 nF

047 F

10 H

410pF

20

20

300 pF

27 nH

27 nH

3 nF

3 nF

20 nH

20 nH

01 F

161

91

MRF 154

MRF 154

1 KW PUSH-PULL RF POWER AMPLIFIER

RFin

RFout

Note gate bias circuits not shown

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

Sidebandfilter

Microphone

Audioamplifier

Linear driver amplifier

AntennaTYPICAL SSB TRANSMITTER

Balancedmodulator

Speechprocessing

Carrieroscillator

Linear poweramplifier

LO

MixerBuffer Tunedcircuit

Phasemodulator

Microphone

Audioamplifier

Driver

TYPICAL FM TRANSMITTERUSING INDIRECT FM

Speechprocessing

Carrieroscillator

Final poweramplifier

Buffer Frequency multipliers

CLASSES OF AMPLIFIERS

bull Class A

ndash Conducts continuously

ndash Linear lowest distortion

ndash Least efficient (lt50)

bull Class B

ndash Conducts for 180ordm of input

ndash More efficient than class A

ndash Push pull circuit reduces distortion

CLASSES OF AMPLIFIERS (continued)

bull Class Cndash Conducts for less than 180ordmndash Highly efficientndash Generates distortion and harmonics

bull Class D and Endash Switching amplifiersndash Introduce distortion and harmonicsndash Most efficient (gt90)ndash Use BJT and enhancement mode

MOSFETS

Class A Operation

Class B Operation

+50 V

3 nF

047 F

10 H

410pF

20

20

300 pF

27 nH

27 nH

3 nF

3 nF

20 nH

20 nH

01 F

161

91

MRF 154

MRF 154

1 KW PUSH-PULL RF POWER AMPLIFIER

RFin

RFout

Note gate bias circuits not shown

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

Phasemodulator

Microphone

Audioamplifier

Driver

TYPICAL FM TRANSMITTERUSING INDIRECT FM

Speechprocessing

Carrieroscillator

Final poweramplifier

Buffer Frequency multipliers

CLASSES OF AMPLIFIERS

bull Class A

ndash Conducts continuously

ndash Linear lowest distortion

ndash Least efficient (lt50)

bull Class B

ndash Conducts for 180ordm of input

ndash More efficient than class A

ndash Push pull circuit reduces distortion

CLASSES OF AMPLIFIERS (continued)

bull Class Cndash Conducts for less than 180ordmndash Highly efficientndash Generates distortion and harmonics

bull Class D and Endash Switching amplifiersndash Introduce distortion and harmonicsndash Most efficient (gt90)ndash Use BJT and enhancement mode

MOSFETS

Class A Operation

Class B Operation

+50 V

3 nF

047 F

10 H

410pF

20

20

300 pF

27 nH

27 nH

3 nF

3 nF

20 nH

20 nH

01 F

161

91

MRF 154

MRF 154

1 KW PUSH-PULL RF POWER AMPLIFIER

RFin

RFout

Note gate bias circuits not shown

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

CLASSES OF AMPLIFIERS

bull Class A

ndash Conducts continuously

ndash Linear lowest distortion

ndash Least efficient (lt50)

bull Class B

ndash Conducts for 180ordm of input

ndash More efficient than class A

ndash Push pull circuit reduces distortion

CLASSES OF AMPLIFIERS (continued)

bull Class Cndash Conducts for less than 180ordmndash Highly efficientndash Generates distortion and harmonics

bull Class D and Endash Switching amplifiersndash Introduce distortion and harmonicsndash Most efficient (gt90)ndash Use BJT and enhancement mode

MOSFETS

Class A Operation

Class B Operation

+50 V

3 nF

047 F

10 H

410pF

20

20

300 pF

27 nH

27 nH

3 nF

3 nF

20 nH

20 nH

01 F

161

91

MRF 154

MRF 154

1 KW PUSH-PULL RF POWER AMPLIFIER

RFin

RFout

Note gate bias circuits not shown

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

CLASSES OF AMPLIFIERS (continued)

bull Class Cndash Conducts for less than 180ordmndash Highly efficientndash Generates distortion and harmonics

bull Class D and Endash Switching amplifiersndash Introduce distortion and harmonicsndash Most efficient (gt90)ndash Use BJT and enhancement mode

MOSFETS

Class A Operation

Class B Operation

+50 V

3 nF

047 F

10 H

410pF

20

20

300 pF

27 nH

27 nH

3 nF

3 nF

20 nH

20 nH

01 F

161

91

MRF 154

MRF 154

1 KW PUSH-PULL RF POWER AMPLIFIER

RFin

RFout

Note gate bias circuits not shown

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

Class A Operation

Class B Operation

+50 V

3 nF

047 F

10 H

410pF

20

20

300 pF

27 nH

27 nH

3 nF

3 nF

20 nH

20 nH

01 F

161

91

MRF 154

MRF 154

1 KW PUSH-PULL RF POWER AMPLIFIER

RFin

RFout

Note gate bias circuits not shown

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

Class B Operation

+50 V

3 nF

047 F

10 H

410pF

20

20

300 pF

27 nH

27 nH

3 nF

3 nF

20 nH

20 nH

01 F

161

91

MRF 154

MRF 154

1 KW PUSH-PULL RF POWER AMPLIFIER

RFin

RFout

Note gate bias circuits not shown

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

+50 V

3 nF

047 F

10 H

410pF

20

20

300 pF

27 nH

27 nH

3 nF

3 nF

20 nH

20 nH

01 F

161

91

MRF 154

MRF 154

1 KW PUSH-PULL RF POWER AMPLIFIER

RFin

RFout

Note gate bias circuits not shown

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

Negative feedback provides stability and wideband performancePower MOSFETs provide a power gain of 11 to 14 dBToroid input and output transformers provideimpedance matching push-pull operation andbroad-band performance (10 to 90 MHz)

Bias

Bias

Gate bias circuits maintain Class B operation forgood efficiency and minimum distortion

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS

bull Individual RF transistors can achieve power levels up to about 500 watts

bull Using a push pull circuit andor paralleling transistors produces power levels over 1 kW

bull For power levels over 1 kW the outputs of several transistor amplifiers can be combined

bull For power levels over about 2 kW tube amplifiers are easier to implement and cheaper

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

bull Crossover Distortionbull If we look at the diagram for the input and output

waveform webull can see some distortion at the cross over where one

transistorbull stops conducting and the other one starts to conductbull 1048708 A small base-emitter voltage is needed to turn on abull transistorbull 1048708 QN actually only conducts when vin gt 07 Vbull 1048708 QP actually only conducts when vin lt -07 Vbull 1048708 When 07 gt vin gt -07 nothing conducts and the output isbull zerobull 1048708 ie the input-output relationship is not at all linear

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

Class C Amplifier

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

IMPEDANCE MATCHING NETWORKS

bull Impedance matching networks are used between amplifier stages and between the final amplifier and the antenna load to ensure maximum power transfer

bull Impedance matching networks consist or inductors and capacitors combined in T or L configurations

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

TRANSFORMERS AND BALUNS

bull Transformers are widely used between amplifier stages for impedance matching

bull A balun is a special type of transformer that is also used for impedance matching between stages

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS

SPEECH PROCESSING CIRCUITS

bull Special circuits are used to modify and enhance the voice signal from the microphone

bull Speech processing includes filtering level-clipping or compressing to minimize bandwidth

bull In modern wireless equipment speech processing is performed by a digital signal processor (DSP)

• Slide 1
• TRANSMITTER COMPONENTS
• Slide 3
• Slide 4
• Slide 5
• CLASSES OF AMPLIFIERS
• CLASSES OF AMPLIFIERS (continued)
• Class A Operation
• Class B Operation
• Slide 10
• Slide 11
• TUBES VERSUS TRANSISTORS IN POWER AMPLIFIERS
• Slide 13
• Slide 14
• Class C Amplifier
• IMPEDANCE MATCHING NETWORKS
• TRANSFORMERS AND BALUNS
• SPEECH PROCESSING CIRCUITS