Physical-Layer RF Design of Dual-Band 802.11 WLANDesign Example: Dual-Band WLAN RF Module IV....

1Wireless Communication LabCCU-EE

Physical-Layer RF Design of Dual-Band 802.11 WLAN

The 13th Annual Wireless & Optical Communication The 13th Annual Wireless & Optical Communication Conference 2004Conference 2004

Sheng-Fuh Chang, Associate ProfessorCenter of Telecommunication Research

Department of Electrical EngineeringNational Chung Cheng University

(05)2720411-33218, Fax:(05)2720862, [email protected] 8, 2004


Contents

I. Motivation of this research

II. RF Design Requirements from 802.11 PHY Clauses

III. Design Example: Dual-Band WLAN RF Module

IV. Conclusions


I. Motivation of the Research

How do we turn 802.11 WLAN RF written documentinto a physical module?


II. RF Requirements from 802.11 PHY Clauses

IEEE802.11a-Subclause 17.3 OFDM PLCP(Physical Layer Convergence Procedure) Sublayer

IEEE802.11b-Subclause 18.4High Rate PMD(physical medium dependent) Sublayer

IEEE802.11g-Subclause 19.4


(I) Operation Frequency Band and channel number

IEEE802.11a 17.3.8.3

Channel Center Frequency=5000 + 5nch (MHz), where nch=0,1,…,200

Lower Band Edge20 MHz

5725

Frequency(MHz)

IEEE802.11a

582551505180

Ch36

5200

40 44

5220

48

5240

52

5260

56

5280

60

5300

64

5320

Upper Band Edge20 MHz

Lower Band Edge 30 MHz Guardband

5350

Upper Band Edge30 MHz

5745

149

5765

153

5785

157

5805

161


1 3

1 6 11

5 7 9 11

Frequency(MHz)2483.52400 2412 2437 2462

• North American channel selection—non-overlapping

24622483.52400

2412 24422422 2432 2452 2472

• North American channel selection—overlapping

IEEE802.11b/g 18.4.6.7.2 Operating channels

Related to Transceiver architecture, VCO and Frequency Synthesizer Design


Straight-forward architecture: Two separated RF Transceiver

Q Data

I Data

I Out

Q OutVGC

090

/2

LPF∑

ADC

ADC

ADC

ADCPowerAmp

DriverAmp

LNA

T/RswitchRF filterAnt

switch

RFmixer

RFmixer

5.2 GHz

PLL

VCO

Q Data

I Data

I Out

Q OutVGC

090

/2

LPF∑

ADC

ADC

ADC

ADCPowerAmp

DriverAmp

LNA


switch

RFmixer

RFmixer

2.4 GHz

PLL

VCO

5.2 GHz

2.4 GHz


Cost-Effective architecture: Dualband RF Transceiver

Q Data

I Data

I Out

Q OutVGC

090

/2

LPF∑

ADC

ADC

ADC

ADC

Q Data

I Data

I Out

Q OutVGC

090

/2

LPF∑

ADC

ADC

ADC

ADC

PLL

VCO

5.2 GHz

PLL

VCO

2.4 GHz

PowerAmp

DriverAmp

LNA


switch

RFmixer

RFmixer

5.2 GHz

PowerAmp

DriverAmp

LNA


switch

RFmixer

RFmixer

2.4 GHz

PowerAmp

DriverAmp

LNA


switch

RFmixer

RFmixer

2.4/5.2 GHz

PLL

VCO

2.4/5.2 GHz


single PLL and VCO generates all RF channels in 2.4 and 5.2 GHz Band

LNA

RFfilter

GainAmp

Q Data

I Data

I Out

Q Out

VGC

LPF

0

90

0

902

LPF

RFMD RF2948

∑

ADCADC

ADCADC

DACDAC

DACDAC

Ant

switchT/RswitchT/Rswitch

2400~2483.5MHz5150~5350 MHz

PowerAmpPowerAmpPowerAmp

DriverAmpDriverAmp

Ant

SAW

LCVariableGain Amp

Imageflter

LO1

LO2Fref

2÷2÷

2÷

P÷

P÷

PFD

PFD

5.2 GHz2.4 GHz


310 MHz Tuning Range

Phase Noise: -96 dBc/Hz @100kHz offset

VCO must have• adequate frequency tuning range•Low phase noise


PLL Loop filter design

Loop filter is designed with compromise among

•stability (phase margin),

• carrier frequency settling time (Lock time), and

• phase noise and interfering spurs.


-97.8 dBc/Hz phase noise at 100 kHz off 5693 MHz 124 µS settling time

Dual-Band Frequency Synthesizer

-67 dB spur level


(1) Concurrent Dual-Band LNA- Circuit 1

NE3210s01NE3210s01

+3.5V+3.5V -0.3V-0.3V

Frequency(GHz)

0 1 2 3 4 5 6 7 8 9

(dB)

-60

-40

-20

0

20

40

S21 simulationS21 measurement


(2) Dual-Band PA

Frequency(GHz)

1 2 3 4 5 6 7

dB

-30

-20

-10

0

10

20

30

S11

S21

S22


(3) Dual-Band Filter

Frequency (GHz)

0 2 4 6 8 10

dB

-60

-50

-40

-30

-20

-10

0

Return lossInsertion loss

Second-order SIR filter


(4) Dual-Band Switch

Frequency (GHz)

1 2 3 4 5 6 7 8 9 10

Inse

rtion

Los

s (d

B)

-12

-10

-8

-6

-4

-2

0

simulationmeasurement

Frequency (GHz)

1 2 3 4 5 6 7 8 9 10

Isol

atio

n (d

B)

-70

-60

-50

-40

-30

-20

-10

simulationmeasurementpost simulation

Rx

LA1

CA1

CA2

Vc1 LA2

Vc1

CA3

Vc1

CA4

QA1

QA2

QA3

Ant

LB1

CB1

CB2

Vc2LB2

Vc2

Tx

CB3

Vc2

CB4

QB1

QB2

QB3


(II) Transmit power levels and spectrum mask

A. Transmit power levels

IEEE802.11a - 17.3.9.1：

40 mW(16dBm)

5150-5250MHz

200 mW(23dBm)

5250-5350 MHz

800 mW(29dBm)

5725-5825 MHz

Frequency(MHz)5180

Ch36 52

52605745

149

582551505200

40 44

5220

48

5240

56

5280

60

5300

64

53205765

153

5785

157

5805

161


IEEE802.11b - 18.4.7.1：1000mW(USA)

100mW(Europe)

10mW/MHz(Japan)

IEEE802.11g - 19.4.7.1：same as 18.4.7.1

1 3 5 7 9 11

2462 2483.52400 2412 24422422 2432 2452 2472

• USA 1000mW • Europe

2483.52400 2412 2442 24622422 2432 2452 2472

1 3 5 7 9 1111 13

100 mW


B. Transmit Spectrum Mask

IEEE802.11b：18.4.7.3IEEE802.11a：17.3.9.2

-30 -20 -11-9 911 20 30Fc

Transmit spectrum mask

transmit spectrum mask

typical signal spectrum(an example)

* The transmitted bandwidth shall have not exceeding 18 MHz

-20dBr

-28dBr

-40dBr

* using 100KHz RBW and 30KHz VBW

Frequency(MHz)


Related to Power Amplifier, RF Filter, RF Switch

LNA

RFfilter

GainAmp

Q Data

I Data

I Out

Q Out

VGC

LPF

0

90

0

902

LPF

RFMD RF2948

∑

ADCADC

ADCADC

DACDAC

DACDAC

Ant


2400~2483.5MHz5150~5350 MHz


DriverAmpDriverAmp

Ant

SAW

LCVariableGain Amp

Imageflter

LO1

LO2Fref

2÷2÷

2÷

P÷

P÷

PFD

PFD


Example: 2.4 GHz Class-AB PA

Frequency 2400-2500 MHz

Output P1dB 24.5 dBm

Output IP3 39.5 dBm

Power gain 14dB

Input return loss >8dB

Output return loss >10dB

@ 24outPAE P dBm= 38%

DC bias 5V;150mA


EVM=4.1%(-13.8 dB)

2.35 2.36 2.37 2.38 2.39 2.4 2.41 2.42 2.43 2.44 2.45-90

-80

-70

-60

-50

-40

-30

-20

-10

0

freq(GHz)

dBm

ACPR< -35dBc

PA is driven to have 22.5 dBmoutput power

PA is driven to have 13.5 dBmoutput power

2.35 2.36 2.37 2.38 2.39 2.4 2.41 2.42 2.43 2.44 2.45-90

-80

-70

-60

-50

-40

-30

-20

-10

0

freq(GHz)

dBm

ACPR < -55dBc

EVM=1.3%(-18.8 dB)


(III) Allowed constellation error and modulation accuracy

A. Allowed relative constellation error

IEEE802.11a：17.3.9.6.3 IEEE802.11b：18.4.7.8

Worst-case vector error magnitude shall not exceeded 0.35 (-4.55dB) for the normalized sampled chip data.


B. Modulation Accuracy

17.3.9.6.1 Transmit Center Frequency Leakage <-15 dB relative to overall transmitted power

e.g. 23 dBm transmitted power, 8 dBm center leakage powerFFT Spectrum

Frequency / MHz1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

-111

-101

-91

-81

-71

-61

-51

-41

-31

-21

-11

<-15 dBr

Center frequency

subcarrierfrequencies

subcarrierfrequencies


Related to baseband IQ Mixer, RF mixer

LNA

RFfilter

GainAmp

Q Data

I Data

I Out

Q Out

VGC

LPF

0

90

0

9042

LPF

RFMD RF2948

∑

ADCADC

ADCADC

DACDAC

DACDAC

Antswitch T/R

switchT/R

switch

2400~2483.5 MHz5150~5350 MHz


DriverAmp

DriverAmp

Ant

SAW

LC VariableGain Amp

Imageflter

LO1

LO2Fref

2÷2÷

2÷

P÷

P÷

PFD

PFD

FFT Spectrum

Frequency / MHz1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 201

-111

-101

-91

-81

-71

-61

-51

-41

-31

-21

-11

FFT Spectrum

Frequency / MHz1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 201

-111

-101

-91

-81

-71

-61

-51

-41

-31

-21

-11

IQ MixerRF Mixer


(IV) Receiver Dynamic Range

A. Receiver minimum input level sensitivity

IEEE802.11a：17.3.10.1 IEEE802.11b：18.4.8.1Minimum Input Power at the Antenna Connector for Packet Error Rate < 10% at a PSDU length of 1000 bytes

-76 dBm at antenna port for frame error ratio (FER)<8% at a PSDU length of 1024 octets.This FER shall be specified for 11 Mbit/s CCK modulation

-6554-6648-7036-7423-7718-7912-819-826

Minimum power at antenna port (dBm)

Data Rate (bits/s)


B. Receiver Maximum Input level

IEEE802.11a：17.3.10.4

• –30 dBm measured at the antenna connector for a maximum Packet Error Rate < 10% at a PSDU length of 1000 bytes

IEEE802.11b：18.4.8.2

• –10 dBm measured at the antenna for a maximum FER of 8% at a

PSDU length of 1024 octets.

• This FER shall be specified for 11 Mbit/s CCK modulation.

IEEE802.11g：19.5.3

–20 dBm measured at the antenna connector for the PER less than 10% at a PSDU length of 1000 bytes for any supported modulation signal or data rate (i.e., 1, 2, 5.5, 6, 9, 11, 12, 18, 22, 24, 33, 36, 48, 54 Mbit/s).


EVM Measurement by HP89441

Input Power(dBm)

-90 -80 -70 -60 -50 -40 -30 -20 -10

EV

M(%

)

0

5

10

15

20

25

30

BPSK & Data Rate: 6Mbits/sBPSK & Data Rate: 9Mbits/sQPSK & Data Rate: 12Mbits/sQPSK & Data Rate: 18Mbits/s16QAM & Data Rate: 24Mbits/s16QAM & Data Rate: 36Mbits/s

65 dB dynamic range of 17% EVM


(V) Adjacent Channel Rejection

A. Adjacent Channel Rejection

IEEE802.11a：17.3.10.2

Interfering Signal Power at Adjacent Channel, referenced to the Desired Signal Level set at 3 dB above the Sensitivity, for Packet Error Rate < 10% at a PSDU length of 1000 bytes

Frequency (MHz)5150

5828M M+1M-1

For example:

Desired Signal :

-79 dBm, 6 Mbps OFDM

Adjacent Signal :

6 Mbps OFDM

> 16 dB

3 dB sensitivity


IEEE802.11b：18.4.8.3The adjacent channel rejection shall be equal to or better than 35 dB, with an FER of 8×10–2 using 11 Mbit/s CCK modulation and a PSDU length of 1024 octets.

adjacent Signal :

11 Mbps CCK

Frequency (MHz)2400

6 dB sensitivity

For example:

Desired Signal :

-70 dBm, 11 Mbps CCK

> 35 dB

2483.5≧25MHz


IEEE802.11g: 19.5 ERP operation specifications

19.5.2 Adjacent channel rejection

For an OFDM PHY the corresponding rejection shall be no less than specified in Table 91 of 17.3.10.(IEEE802.11a)

The adjacent channel rejection of the ERP-DSSS modes shall follow 18.4.8.3 (IEEE802.11b)

19.6 ER-PBCC operation specifications

19.6.2 Receiver adjacent channel rejection

The adjacent channel rejection shall be equal to or better than 35 dB, with an FER of 8×10 –2 using ER-PBCC modulation and a PSDU length of 1024 octets


B. Non-adjacent Channel Rejection

Interfering Signal Power at Non-adjacent Channel, referenced to the Desired Signal Level set at 3 dB above the Sensitivity, for Packet Error Rate < 10% at a PSDU length of 1000 bytes


Non-adjacent Signal :

6 Mbps OFDM

Frequency (MHz)5150 5828M M+1M-1

For example:

Desired Signal :

-79 dBm, 6 Mbps OFDM

> 32 dB

3 dB sensitivity


LNA

RFfilter

GainAmp

Q Data

I Data

I Out

Q Out

VGC

LPF

0

90

0

9042

LPF

RFMD RF2948

∑

ADCADC

ADCADC

DACDAC

DACDAC

Antswitch T/R

switchT/R

switch

2400~2483.5 MHz5150~5350 MHz


DriverAmp

DriverAmp

Ant

SAW

LC VariableGain Amp

Imageflter

LO1

LO2Fref

2÷2÷

2÷

P÷

P÷

PFD

PFD

Related to Channel Selection Filter(IF SAW, Baseband Digital Filter)


How do we achieve?


III. Design Example: Dual-Band WLAN RF Module

(A) RF Transceiver Architecture and Frequency Plan

(B) Transmitter Power Budget

(C) Receiver Gain Budget

(D) Key Components Design

(E) Module Integration


(A) RF Transceiver Architecture and Frequency Plan

LNA

RFfilter

GainAmp

Q Data

I Data

I Out

Q Out

VGC

LPF

0

90

0

902

LPF

RFMD RF2948

∑

ADCADC

ADCADC

DACDAC

DACDAC

Ant


2400~2483.5MHz5150~5350 MHz


DriverAmpDriverAmp

Ant

SAW

LCVariableGain Amp

Imageflter

LO1

LO2Fref

2÷2÷

2÷

P÷

P÷

PFD

PFD


Frequency Planning for 802.11a/b/g RF Transceiver(a) fixed IF or floating IF(b) LO frequency range

Share same frequency synthesizer to save component count and DC power consumption

802.11b/g RF802.11b/g LO

802.11a RF802.11a LO

fixed IF802.11b/g LO 802.11a LO


(B) Transmitter Power Budget

IEEE80211b/g Power Budget

VGA

BPF

Mix

1

Imag

e_fil

ter

Driv

er_A

mp

PA

Switc

h1

RF_

filte

r

Ant_

switc

h

Pow

er(d

Bm

)

-20

-10

0

10

20

30

40

Output P1dB

Pin=-2 dBm

(CW) 11 Mbps DQPSK

OFDM 54 Mbps 64QAM


IEEE802.11a Power Budget

VGA

BPF

Mix

1

Imag

e_fil

ter

Drive

r_Am

p

PA

Switc

h1

RF_f

ilter

Ant_

switc

h

Powe

r(dBm

)

-20

-10

0

10

20

30

40

Output P1dB

Pin=-2 dBm

OFDM 54 Mbps 64QAM


(C) Receiver Gain Budget

IEEE802.11b/g Power Budget

Ant_

Switc

h

RF_

filte

r

Sw

itch1

LNA

Imag

e_fil

ter

Mix

1

SAW

IF_a

mp

Pow

er(d

Bm

)

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

Output P1dB

Pin=-76 dBm

Pin=-20 dBm

dynamic range

IEEE802.11a Power Budget

Ant_

Switc

h

RF_

filte

r

Switc

h1

LNA

Imag

e_fil

ter

Mix

1

SAW

IF_a

mp

Pow

er(d

Bm

)-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

Output P1dB

Pin=-30 dBm

Pin=-82 dBm

dynamic range


(D) Dual-Band RF Key Component Design

Concurrent Dual-band LNA

Concurrent Dual-band PA

Concurrent Dual-Band Filter

Concurrent Dual-Band Switch

VCO and Frequency Synthesizer


(1) Concurrent Dual-Band LNA- Circuit 1

NE3210s01NE3210s01

+3.5V+3.5V -0.3V-0.3V

Frequency(GHz)

0 1 2 3 4 5 6 7 8 9

(dB)

-60

-40

-20

0

20

40

S21 simulationS21 measurement


(1) Concurrent Dual-Band LNA- 0.18umCMOS

RF_in +

Vcc

Vg

Vcc

Vcc Vcc

Vg

RF_in -

RF_out + RF_out -

L1 L2

C1C2

M1 M2

M3 M4

C3 C4

L7L8L6

L5

C8 C9 C10

C7

Pad andbondwire

Freq. (GHz)

0 2 4 6 8 10

S21

(dB

)

-50

-40

-30

-20

-10

0

10

20

SimulationMeasurement


(2) Dual-Band PA

Frequency(GHz)

1 2 3 4 5 6 7

dB

-30

-20

-10

0

10

20

30

S11

S21

S22


(3) Dual-Band Filter

Frequency (GHz)

0 2 4 6 8 10

dB

-60

-50

-40

-30

-20

-10

0

Return lossInsertion loss

Second-order SIR filter


(4) Dual-Band Switch

Frequency (GHz)

1 2 3 4 5 6 7 8 9 10

Inse

rtion

Los

s (d

B)

-12

-10

-8

-6

-4

-2

0

simulationmeasurement

Frequency (GHz)

1 2 3 4 5 6 7 8 9 10

Isol

atio

n (d

B)

-70

-60

-50

-40

-30

-20

-10

simulationmeasurementpost simulation

Rx

LA1

CA1

CA2

Vc1 LA2

Vc1

CA3

Vc1

CA4

QA1

QA2

QA3

Ant

LB1

CB1

CB2

Vc2LB2

Vc2

Tx

CB3

Vc2

CB4

QB1

QB2

QB3


(5) Dual-Band VCO and Frequency Synthesizer

310 MHz Tuning Range

5.6 GHz VCO

VCO out

Vcc

V tune

Vcc

BFG425 BFG425

Colpitts

Phase Noise: -95.95dBc/Hz@100kHz offset


5.6 GHz 0.18um CMOS quadrature VCO

-113 dBc/Hz at 1 MHz off

3o phase imbalance

VDD

Vbias

VCNTL

IOUT+

MA1

VDD

MA2 MB2MB1MA3 MA4 MB4MB3

MA5 MB5

MA6 MA7

IOUT- QOUT+ QOUT-

VbiasVbiasVbias

VCNTL MB6 MB7

PAD


8 synthesized carriers

-67 dBC spur level


-97.8 dBc/Hz phase noise at 100 kHz off carrier

124 µS settling time


(E) 2.4/5.2-GHz RF Integration

IF IQ modemDualbandreceiver Frontend

Dualbandtransmitter frontend

Antenna diversity switch

Dualband frequency synthesizer

RF-BB inter-face


(I) 2.4/5.2-GHz RF receiver test

2.4 GHz CCK QPSK 11 Mbps:

EVM=6.86 % (-60dBm received power)

2.4 GHz 64QAM 54 Mbps：

EVM=6.2 % ( -60dBm received power)


5.2 GHz 64QAM 54 Mbps:EVM=4.05 % ( -60dBm received power)



Input Power(dBm)

-90 -80 -70 -60 -50 -40 -30 -20 -10

EV

M(%

)

0

5

10

15

20

25

30


5.2 GHz Band

65 dB dynamic range for 17% EVM


Input Power(dBm)

-90 -80 -70 -60 -50 -40 -30 -20 -10

EV

M(%

)

0

5

10

15

20

25

30

35

40


RX(with IF IQ modem) Dynamic Range Test

2.4 GHz Band

70 dB dynamic range for 17% EVM


(II) 2.4/5.2-GHz RF transmitter test

2.4 GHz 54 Mbps 64QAM:

EVM=5.1%=-25.9 dB

2.4 GHz 12 Mbps QPSK:

EVM=5.8%=-24.7 dB


5.2 GHz 64QAM 54 Mbps:

EVM=4.46 %=-27.0 dB


IV. Conclusion

Transform of a written document into a physical module


Examine 802.11a/b/g RF specifications

Determine RF transceiver architecture

Calculate and simulate RF transceiver link budget

Design RF key circuits-MMIC, HMIC

RF Module Integration and measurement


Thank you

Sincerely appreciate ISSC for partial funding support

Date post:	07-Mar-2020
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Physical-Layer RF Design of Dual-Band 802.11 WLANDesign Example: Dual-Band WLAN RF Module IV....

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