Microwave Technology - Faculty of Information Engineering ... · – Noise, Microwave Sources,...

GUC (Dr. Hany Hammad) 9/5/2016

COMM (903) Lecture # 1 1

© Dr. Hany Hammad, German University in Cairo

(COMM 903)

Microwave Technology


Contents

• Introduction:

– Course contents.

– Assessment.

– References.

• Microwave Sources.

• Transistor Model Extraction.

• Signal flow graphs.




Course Contents

• Active Microwave & RF Circuits Analysis & Design

– Noise, Microwave Sources, Amplifiers, Mixers & Oscillators.

• Metamaterials and Transmission Lines

– Basic properties, Transmission Line Implementations and Applications.


Teaching Assistant (Tutorials)

Engs. Randa El Khosht

References

David M. Pozar, “Microwave Engineering”, 3rd Edition, Wiley. Lecture Notes

Eng. Yasmine Abdella

Teaching Assistant (Advanced Comm. Lab.)




Assessment

Quizzes (2-3) 15

Tutorial Assignments 5

Project 10

Mid Term Examination 25

Final Examination 45

Total 100


Microwave Sources

Low Power &

Low Frequencies

Sources

High Power &/or

high frequencies Sources

Solid State Sources Microwave Tubes

Microwave Engineering, 3rd Edition by David M. Pozar

Copyright © 2004 John Wiley & Sons




Microwave Tubes

Types of Microwave Tubes:

– Klystron

– TWT (Traveling Wave Tubes)

• Helix TWT.

• Coupled cavity TWT.

– Magnetron.

– Gyroton.

– Gridded Tube.

– CFA (crossed field amplifiers)


Solid State Sources

• Advantages:

– Small Size.

– Low Cost.

– Compatibility with microwave integrated circuits.

• Disadvantages:

– Low power.

– Low frequencies.




Solid State Sources

• Can be categorized as:

– Two terminal devices

• Ex.: Diodes.

– Three terminal devices

• Ex.: Transistor oscillators.


Diode Sources

• Most common diode sources:

– Gunn diode.

– IMPATT diode.

• Directly convert DC bias to RF power in the frequency range of 2 to 100 GHz.




Gunn Diode

• Even though everyone uses this term! It’s more accurate name is a “Transferred Electron Device” (TED). Why isn't it a "real" diode? Because it only uses N-type semiconductor.

• Gunn diodes have been around since John Gunn discovered that bulk N-type GaAs can be made to have a negative resistance effect.

• Three regions exist: two of them are heavily N-doped on each terminal, with a thin layer of lightly doped material in between.

Broadband Microwave Amplifiers by Bal S. Virdee, Avtar S. Virdee, & Ben Y. Banyamin

Copyright © 2004 Artech House


Gunn Diode

Two Gunn diode sources. The unit on the left is a mechanically tunable E-band source, while the

unit on the right is a varactor-tuned V-band source.

Microwave Engineering, 3rd Edition by David M. Pozar

Copyright © 2004 John Wiley & Sons



FET


Small Signal Models





The GaAs MESFET Structure

Cross sectional view of the GaAs MESFET structure shows the depletion region below the gate

The contact of the gate is made of metal-semiconductor Schottky Contact rather than a metal-oxide-semiconductor (MOS) structure, which is used in the MOSFET device. This approach minimizes the device’s gate to source capacitance, which otherwise would degrade the high-frequency gain performance.




The GaAs MESFET

d

satsm

h

vwg

gm= intrinsic device transconductance hd= depletion-layer depth w = gate width s= semiconductor dielectric constant vsat= saturated carrier velocity

gs

mT

C

gf

2 fT = Unity-current-gain frequency

Cgs= gate to source capacitance

At frequencies above fT the current passing through the Cgs is greater than that produced by the transconductance, therefore, fT represents a

fundamental high-frequency limit.

d

gs

gsh

lwC

g

satT

l

vf

2

For optimum high-frequency performance, the device designer must either increase the saturated carrier velocity or decrease the gate length.




Device Characterization and Modeling

• Small signal model Intrinsic & Extrinsic elements is determined using the hot and cold deembedded S-parameters measurements.

• Large Signal model is determined by using the semi-empirical method, and it uses the measured pulsed dc I-V data of the device and no assumptions are made relating to the physical operation of the device itself.

• One key issue in S-parameters measurements is the accurate calibration of the network analyzer. The calibration of the instrument should remove unwanted and repeatable information, such as the effects of non-ideal transmission lines, connectors, and circuit parasitic.


Small-signal device modeling procedure

Cold Vds = 0 V Vgs = -3 V (pinch off)






Hot S-parameters Extraction

Cdc = diople layer capacitance

The extrinsic parameters Cgp, Cdp, Lg, Ld, Rg, Rs and Rd. The gate and drain bond-pad capacitance (Cpg and Cpd) in the modeling process.

Rg & Rd represent the device’s gate and drain resistance. Rs & Ls are the source resistance and inductance.




Cold S-parameters Extraction






Cold S-parameters Extraction

absgsgc CLLjRRZ 111

bsscc CLjRZZ 12112

bcsdsdc CLLjRRZ 122

111 baab CCC 111 cbbc CCC

1211Re ccg ZZR

12Re cs ZR

1222Re ccd ZZR

absgc CLLZ 1Im 2

11

bsc CLZ 1Im 2

12

bcsdc CLLZ 1Im 2

22


Hot S-parameters Extraction

gsi

gdCjR

CjY

1

111

gdCjY 12

gdgsi

j

mo CjCRjegY 121

gdds

ds

CCjR

Y 1

22



gsv+

-

j

mom egg




Model Extraction

12Im YCgd

2

11

2

1111

Im

Re1

Im

gd

gd

gsCY

YCYC

2

11

2

1111 ReImRe YCYYR gdi

2222

11

2

21 1)Im(Re igsgdmo RCCYYg

moigsgd gRCYYC 2121

1 ReImsin/1

gdds CYC 22Im

22Re1 YRds

j

mm eggo


S-parameters files




Extraction Steps

• Measure the S-parameters and save as .s2p file.

• Load file into Matlab (load file name.s2p)

• Convert the s2p to y-parameters using the equations (or using s2y command in matlab.

dsR dsCgsmvg

iR

gdC

gsC

Gate Drain

Source

+

-

gsv

I1 I2

V1 V2

2121111 VYVYI

2221212 VYVYI

MESFET Model Extraction Project



In case of V2=0

dsR dsCgsmvg

iR

gdC

gsC

Gate Drain

Source

+

-

gsv

I1 I2

V1 V2=0

gsmvg

iR

gdC

gsC

Gate

Source

+

-

gsv

I1 I2

V1 V2=0

Drain

Finding Y11 & Y21

gsmgd vgCjVI 12

igsgsi

gs

gsRCj

V

CjR

CjVv

11

111

igs

mgd

RCj

VgCjVI

1

112

gd

igs

m

V

CjRCj

g

V

IY

1

01

221

2

gsi

gd

VCjR

CjV

IY

1

1

01

111

2

gsmvg

iR

gsC

Gate

Source

+

-

gsv

I1 I2

V1 V2=0

gdCjV 1

Finding Y11 & Y21



igs

igs

igs

gs

gd

igs

gs

gdRCj

RCj

RCj

CjCj

RCj

CjCjY

1

1

1111

222

22

111 igs

igsgs

gdRC

RCCjCjY

2221 igsRCD

gd

gsigsC

D

Cj

D

RCY

22

11

Finding Y11 & Y21

dsR dsCgsmvg

iR

gdC

gsC

Gate Drain

Source

+

- gsv

I1 I2

V1

V2

dsR dsC

gdCGate

Drain

Source

I1 I2

V1

V2 gdds

dsV

CCjRV

IY

1

02

222

1

gd

V

CjV

IY

02

112

1

Finding Y11 & Y21



pFFCgd 02548.0102548.2 14

pFFCgs 11782.0101782.1 13

3838.7iR

Sgm 0664.0

sec35229.0sec105229.3 13 p

pFFCds 47753.0107753.4 14

924.198dsR

Extracted Model Parameters

NE321000 Vds = 2 V Id = 10 mA

0 5 10 15 20 25 30-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4x 10

-3

freq. (GHz)

e(Y

11)

(S)

Measured

Calculated

0 5 10 15 20 25 300

0.005

0.01

0.015

0.02

0.025

0.03

freq. (GHz)

m

(Y11)

(S)

Measured

Calculated

Results Y11 (Measured Vs Calculated from extracted Model)



0 5 10 15 20 25 30-3

-2.5

-2

-1.5

-1

-0.5

0

0.5x 10

-4

freq. (GHz)

e(Y

12)

(S)

Measured

Calculated

0 5 10 15 20 25 30-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0x 10

-3

freq. (GHz)

m

(Y12)

(S)

Measured

Calculated


0 5 10 15 20 25 300.058

0.06

0.062

0.064

0.066

0.068

0.07

0.072

0.074

freq. (GHz)

e(Y

21)

(S)

Measured

Calculated

0 5 10 15 20 25 30-0.025

-0.02

-0.015

-0.01

-0.005

0

freq. (GHz)

m

(Y21)

(S)

Measured

Calculated




0 5 10 15 20 25 304.7

4.8

4.9

5

5.1

5.2

5.3x 10

-3

freq. (GHz)

(Y

22)

(S)

Measured

Calculated

0 5 10 15 20 25 300

0.002

0.004

0.006

0.008

0.01

0.012

0.014

freq. (GHz)

m

(Y22)

(S)

Measured

Calculated


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