In partnership with STMicroelectronics

DESIGN OF A CLASS 1 POWER AMPLIFIER FOR BLUETOOTHTM

APPLICATIONS

Advisors CandidateProf. Antonella D’Orazio Giovanni DE FILIPPO

Tutor .

Dr. Roberto Antonicelli .

A.Y. 2004-05

Politecnico di BariEngineering Faculty - Electronics Engineering Course

Thesis in MICROWAVES

OUTLINE

CHECK OF SUITABLE COMPONENTSDESIGN AND ANALYSIS USING ANSOFT

DESIGNER SVREALIZATIONMEASUREMENTSSTLC2500 WITH CLASS 1 PA

IMPLEMENTATION

DESIGN CHALLENGES

LOW COST HIGH POWER GAIN MINIMAL BOM

ELECTRICAL SPECIFICATIONS

Central Frequency: 2.45 GHz Bandwidth: 100 MHz Input and Output Impedance: 50 Ohms Output Powers: 10, 14 and 18 dBm Supply Voltage: 2.75 Volts Operating Temperature: -40 to +85°C

DESIGN MODEL

2.7

5

A

B

PA_EN

TR1

L1

C4

C1

C5

L2

C2

L3

L4

C3

TR2R6

R5R3 R4

TR3

R2

R1

Input Matching DC Block

Output Matching DC Block

Enable and Power Control

RF Choke to DC Bias

Biasing Transistor

DESIGN MODEL

Input Matching DC Block

Output Matching DC Block

Trasmission Line ModelRF Power

Transistor

RF Choke to DC Bias

ANALYSIS

S11 and S22 at 2.45 GHz

Gain from 500 MHz to 3 GHz

ANALYSIS

Stability factor from 500 MHz to 3 GHz

Input and output return loss from 500 MHz to 3 GHz

REALIZATION

PCB Layout

Photograph of the Class 1 PA

MEASUREMENTS

Photograph of the Test Setup

Class 1 Power Amplifier and Measurement Setup

MEASUREMENTS

S11 in Bluetooth Band

S22 in Bluetooth Band

MEASUREMENTS

Pout, Gain and efficiency vs Pin @ 2450 Mhz

-25-23-21-19-17-15-13-11

-9-7-5-3-113579

1113151719212325

-20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10

Pin (dBm)

Ga

in (

dB

)P

ou

t (d

Bm

)

0,0

5,0

10,0

15,0

20,0

25,0

30,0

35,0

40,0

45,0

50,0

55,0

60,0

65,0

70,0

Eff

icie

nc

y (

%)

Gain (dB) Pout (dBm) Efficiency (%)

Gain, Output Power and Efficiency versus Input Power at 27 °C

MEASUREMENTS

Pout vs Pin @ varius temperatures, Vce=2,75V

-20-18-16-14-12-10

-8-6-4-202468

101214161820

-20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10

Pin (dBm)

Po

ut

(dB

m)

-40°C 27°C 85°C

Efficiency vs Pin @ varius temperatures, Vce=2,75V

0,0

5,0

10,0

15,0

20,0

25,0

30,0

35,0

40,0

45,0

50,0

55,0

60,0

65,0

70,0

-20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10

Pin (dBm)

Eff

icie

nc

y (

%)

-40°C 85°C 27°C

Output Power Efficiency versus

Input Power for different Temperatures

MEASUREMENTS

Pout vs Pin @ varius temperatures, Vce=2,50V

-20-18-16-14-12-10

-8-6-4-202468

101214161820

-20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10

Pin (dBm)

Po

ut (

dB

m)

27°C -40°C 85°C

Efficiency vs Pin @ varius temperatures, Vce=2,50V

0,0

5,0

10,0

15,0

20,0

25,0

30,0

35,0

40,0

45,0

50,0

55,0

60,0

65,0

70,0

-20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10

Pin (dBm)

Eff

icie

ncy

(%)

27°C 85°C -40°C

Pout vs Pin @ varius temperatures, Vce=3,00V

-20-18-16-14-12-10

-8-6-4-202468

101214161820

-20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10

Pin (dBm)

Po

ut (

dB

m)

-40°C 27°C 85°C

Efficiency vs Pin @ varius temperatures, Vce=3,00V

0,0

5,0

10,0

15,0

20,0

25,0

30,0

35,0

40,0

45,0

50,0

55,0

60,0

65,0

70,0

-20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10

Pin (dBm)

Eff

icie

ncy

(%)

-40°C 85°C 27°C

Pout and Efficiency vs Pin at various Temperatures and Vcc

Vcc = 2.50 VVcc = 3.00 V

PERFORMANCE OVERVIEW

Compression Point P-1dB = 20 dBmPower Gain Gp = 12 dBCurrent consumption at max

power Icc = 53 mAAdded Efficiency η = 70 %

STLC2500 CLASS 1 SOLUTION

Output Power

MaxOutputPower

15,2

15,4

15,6

15,8

16

16,2

16,4

16,6

16,824

02

2407

2412

2417

2422

2427

2432

2437

2442

2447

2452

2457

2462

2467

2472

2477

Frequency[MHz]

Max

Ou

tpu

t P

ow

er [

dB

m]

Average

Peak

AcPower - CH 39

-60

-50

-40

-30

-20

-10

0

10

20

2402

2408

2414

2420

2426

2432

2438

2444

2450

2456

2462

2468

2474

2480

Frequency[MHz]

AC

P l

evel

[dB

m]

AcPower-39

Spec

Output Spectrum, Adjacent Channel

Power

STLC2500 CLASS 1 SOLUTION

Output Spectrum

RF = LO – BB = 2.44084 GHzIM = LO + BB = 2.44116 GHzPULLING = LO – 3BB = 2.44052 GHz

Pulling Behavior (Default Gain Setting)

-60

-55

-50

-45

-40

-35

Ch. 0 Ch. 39 Ch. 78

Frequencies

Pu

llin

g

V457CA-Fundamental

V457CA-Harmonic

V457CA+Class1-Fundamental

V457CA+Class1-Harmonic

Pulling Behavior at Default Gain Settings

CONCLUSIONS• Single transistor, small sized Bluetooth Class 1

power amplifier• Lowest cost in marketplace• High gain and high 1 dB-compression point• 12mA of quiescent current and 70% total

efficiency• Single 2.75V supply voltage• Minimum BOM• Stable behavior versus temperature and Vcc