STMicroelectronics

Quad-band GSM Power Amplifier by optimized BCD RFLDMOS

Andrea Pallotta – FTM Smart Power & HV Tech. Department

IEEE Topical Workshop on Power Amplifiers for Wireless Communications, San Diego 15-17 Jan. 2006

ER S T

Reduced Electrosmog Society Technology

This work has been supported and founded by the Italian Research and University Ministry (MIUR) throughout the project:

2ER S T

RF-LDMOS Cross-section

Parameter Value Test Condition BVDSS [V] 16 IDS = 0.01 nA/µm IOFF [pA/µm] <1 VDS = 5 V

VGS = 0 Ron*W [Ω*mm] 2.8 VGS = 3.3 V

VDS = 0.1 V Gm/W [mS/mm] 200 VDS = 3.5 V ISAT/W [mA/mm] 480 VDS = 3.5 V FT [GHz] 18 VDS = 3.5 V

Table I

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W=2.8mm RF-LDMOS load-pull measurements

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W=2.8mm RF-LDMOS W-CDMA ACPR measurements

5ER S T

RF-LDMOS sub circuit model

6ER S T

W=6 mm RF-LDMOS model vs. measurements

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W=12mm RF-LDMOS model vs. measurements

8ER S T

Final power RF-LDMOS transistors for GSM PA

W=24mm

W=12mm

• 120 fingers for each active area

• each finger is 25 µm long

9ER S T

Final power transistor test board

•SMD size: 0.75x1.5 mm (0603)•Board size: 38x51 mm (BT laminate)•Output Matching Network implemented for Harmonic Control

RF out50 ΩRF in

50 Ω

Vg

VDD

10ER S T

CAD optimization maximizing PAE and Pout (W=12mm)

RF out50 ΩRF in

50 Ω

Vg

VDD

1.75 GHzPout = 32.5 dBm

PAE = 48%

1.88 GHzPout = 32 dBm

PAE = 51%

11ER S T

50Ω-50Ω matched final power LDMOS

20

25

30

35

10 12 14 16 18 20 22 24 26Pin (dBm)

Pout

(dB

m)

1520253035404550556065

PAE

(%)

0

5

10

15

20

25

30

35

16 18 20 22 24 26Pin (dBm)

Pout

(dbm

), G

ain

(dB

)

20

25

30

35

40

45

50

55

PAE

(%)

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Quad-band GSM850-900 and GSM 1800-1900 RF PA on PCB in order to validate the RF-BCD technology process

1st 2nd 3rd

Preamp = 0.8 x 1.4 mm Power = 0.6 x 1.3 mm

GSM850-900 board = 38 x 51 mm

1st 2nd 3rd

Preamp = 1 x 1.8 mm Power = 1 x 1.8 mm

DCS-PCS board = 38 x 51 mm

13ER S T

GSM850-900, DCS-PCS Circuit Schematics

LaminatePCB

GSM-850

GSM-900

W=0.1mmM = 8 W=3mm

MOS50 Ω

LaminatePCB

Sidie

W=12mm

50 Ω

Sidie

Sidie

DCSPCS

RF IN

RF OUTM4

Vc

RFinT1 T2 T3 RFout

Bias ControlBias ControlBias Control

GSM Driver

50 Ω50 Ω

Si

die

Si

die

M2

M3M1M4

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GSM850 RF PA main performances

Pin=6dBmPout=35.3dBmPAE=47%

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GSM900 RF PA main performances

Pin=6dBmPout=35.2dBmPAE=55%

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GSM900 RF PA Pout and PAE over frequency

31

31.5

32

32.5

33

33.5

34

34.5

35

35.5

36

840 860 880 900

Frequency (MHz)

Pout

(dB

m)

40

42

44

46

48

50

52

54

56

58

60

PAE

(%)

PoutPAE

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DCS RF PA main performances

Pin=6dBmPout=33dBmPAE=51.4%

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PCS RF PA main performances

Pin=6dBmPout=32.1dBmPAE=47.7%

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Second harmonic level in the upper band

20

22.5

25

27.5

30

32.5

35

1.65 1.7 1.75 1.8 1.85 1.9 1.95 2

Frequency (GHz)

Pou

t (dB

m) @

Pin

= 6

dBm

15

25

35

45

55

65

75

H2 (d

Bc)

Target spec

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1.75GHz: 2-Tone IM3 vs. Input Power

0

10

20

30

40

-8 -3 2 7 12

Pin (dBm)

Pout

, 2-to

ne IM

3 (d

Bm

)

2− tone ∆ f = 5 MHz

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Pout and DC drain current vs. VSWR > 8:1 all phases @ 5 V

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DCS PA on PCB board detail

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GSM850-900, DCS-PCS on board summary

47 / 474751475247PAE (%)

32.5 / 323232.5353535POUT (dBm)

033033PIN (dBm)

SOA*DCS/PCS(module)

PCS(board)

DCS(board)

SOA*GSM

(module)

GSM-900(board)

GSM-850(board)

1.721.741.761.781.801.821.841.861.881.90

1.70

1.92

10152025303540

5

45

-12

-10

-8

-6

-14

-4

Freq, GHz

S21

Mag

(dB)

S11 Mag (dB)

S-parameters DCS-PCS5

1015202530354045

800 840 880 920 960 1000

Freq (GHz)

S21

Mag

(dB

)

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

S11

Mag

(dB

)

S-parameters GSM850-900

* SOA: State Of the Art LDMOS based GSM PA module available on the market

24ER S T

RF front end module moves towards high integration level => LTCC

25ER S T

8x8mm Quad-Band GSM850-900 & DCS-PCS PA on LTCC