rf lab summary

1

RF & Microwave Design and Measurement Laboratory The University of Texas at Dallas

Ahnaf Hassan

Abstract: This lecture and lab course covered fundamentals of microwave design and measurements.

Various microwave components were designed and simulated with CAD tools (Microwave Office, AWR,

AXIEM) and then built and measured to compare performance with theory. The lab involved learning the

basics of accurate microwave measurements, including vector impedance (scattering parameters), scalar

measurements and spectrum analysis.

Keywords: Microwave Office, MWO, AWR, AXIEM, Vector Network Analyzer, VNA, S Parameters,

Resonators, Microstrip, EM Simulation, Power Divider, Coupler, Wilkinson, Filters, LNA, Amplifiers,

MMIC.

i. Introduction

RF components were designed according to given

goals, specified in terms of operating and cutoff

frequencies, gain, return and insertion losses etc.

Microwave Office was used to design and simulate

circuits and microwave implementations. The

components were then milled, and tested in the lab

using network analyzers, power meters etc.

Measured data was compared to simulated

(theoretical) data to test for accuracy and possible

design issues.

ii. Microstrip Resonator

Objective:

Design two quarter-wave resonators, single stub

and double stub, and connect them to a 50Ω

transmission line. In both designs the stub ends

with an open circuit.

Design Goal:

Parameter Design Goal

Resonant Frequency (GHz) 2.5

Input Return Loss (dB) <2

Output Return Loss (dB) <2

Insertion Loss at fo (dB) >20 Table 1: Single Stub Resonator


Resonant Frequency (GHz) 2.5

Input Return Loss (dB) >20

Output Return Loss (dB) >20

Insertion Loss at fo (dB) <1.0 Table 2: Double Stub Resonator

Design:

Single Stub

Figure 1: Circuit Schematic

Figure 2: Board Layout

MLEFID=TL4W=2.96 mmL=16.11 mm

MLINID=TL1W=2.96 mmL=10 mm


MSUBEr=4.45H=1.57 mmT=0.017 mmRho=0.705Tand=0.02ErNom=4.45Name=SUB1

1 2

3

MTEE$ID=TL2MSUB=SUB1

STACKUPName=SUB2

EXTRACTID=EX1EM_Doc="EM_Extract_Doc"Name="EM_Extract"Simulator=AXIEMX_Cell_Size=1 mmY_Cell_Size=1 mmSTACKUP=""Override_Options=YesHierarchy=OffSweepVar_Names=""

PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

2

Figure 3: Milled Design

Double Stub

Figure 4: Circuit Schematic

Figure 5: Board Layout

Figure 6: Milled Design

Performance:

Single Stub

Figure 7: Comparison of simulated and measured data

Double Stub

Figure 8: Comparison of insertion loss

1

2

3

4

MCROSS$ID=TL2






STACKUPName=SUB2


PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

1 2 3 4 5

Frequency (GHz)

Comparison between Measured and Simulated Data

-40

-30

-20

-10

0

2.5 GHz-30.39 dB

2.5 GHz-30.9 dB

2.5 GHz-0.3817 dB

2.5 GHz-0.4127 dB

DB(|S(1,1)|)Single Stub Resonator AXIEM



DB(|S(1,1)|)SS BETTER



3

Figure 9: Comparison of return loss

iii. 3-dB Wilkinson Power Divider

Objective:

Design a microstrip 3-dB Wilkinson power

divider on 1.57mm thick FR-4 material and

compare and contrast simulated and

physical design.

Design Goal:

Parameter Design

Goal

Center Frequency (GHz) 2.5

Power Split -3.0

Insertion Loss <1.0

Relative Phase 0

Input Return Loss >20

Output Return Loss >20

Isolation between Output Ports >20

Table 3: Design goals

Design:

Figure 10: Circuit design

Figure 11: Board layout

Figure 12: Milled design

Performance:

Figure 13: Comparison of input return loss

MCURVE$ID=TL5ANG=90 DegR=0.775 mmMSUB=SUB1







MLINID=TL3W=1.55 mmL=L1 mm




MLINID=TL14W=2.96 mmL=0.762 mm







1

2

3MTEE$ID=TL2MSUB=SUB1

1

2

3

MTEEID=TL4W1=1.55 mmW2=1.55 mmW3=2.96 mmMSUB=SUB1

1

2

3

MTEEID=TL12W1=1.55 mmW2=1.55 mmW3=2.96 mmMSUB=SUB1

RESID=R1R=100 Ohm

STACKUPName=SUB2


PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

PORTP=3Z=50 Ohm

L3=4.93

L2=5.8

L1=6.9

1 2 3 4 5

Frequency (GHz)

Comparison of Input Retun Loss

-50

-40

-30

-20

-10

0

2.5 GHz-29.59 dB

2.53 GHz-29.9 dB

2.5 GHz-21.73 dB

2.763 GHz-41.19 dB

DB(|S(1,1)|)S1TO2 UNTUNED

DB(|S(1,1)|)Winkinson Milled AXIEM

4


Figure 15: Comparison of phase difference

iv. Microwave Directional Coupler

Objective:

Design a 3-dB Quadrature Branch-Line Directional

Coupler (not milled) and a microstrip Edge-Coupled

Coupler (20-dB coupling).

Design Goal:

Branch-line Coupler:



Coupling (dB) 3.0

Relative Phase (deg) 90

Input Return Losses(dB) >20

Isolation @fo (dB) TBD Table 4: Design objectives

Edge-Coupled Coupler:



Coupling (dB) 20.0

Relative Phase (deg) 90


Isolation @fo (dB) TBD Table 5: Design objectives

Design:


Figure 16: Circuit layout



1 2 3 4 5

Frequency (GHz)

Comparison of Insertion Loss

-6

-5.5

-5

-4.5

-4

-3.5

-3

2.5 GHz-3.25 dB

2.5 GHz-3.196 dB 2.5 GHz

-3.273 dB

2.5 GHz-3.269 dB





1 2 3 4 5

Frequency (GHz)

Comparion of Output Port Phase Difference

-1

0

1

2

3

2.5 GHz-0.07258 Deg

2.5 GHz0.8491 Deg

SDeltaP(Winkinson Milled AXIEM,2,1,3,1) (Deg)

Winkinson Milled AXIEM

SDeltaP(S1TO3 UNTUNED,2,1,2,1) (Deg)

S1TO2 UNTUNED

MLINID=TL1W=W_Zo mmL=L_Zo mm

1 2

3

MTEEID=TL2W1=W_Zo mmW2=W_Zosrt2_trans mmW3=W_Zo_trans mm

MLINID=TL3W=W_Zosrt2_trans mmL=L_Zosrt2_trans mm

1 2

3

MTEEID=TL4W1=W_Zosrt2_trans mmW2=W_Zo mmW3=W_Zo_trans mm



12

3

MTEEID=TL7W1=W_Zosrt2_trans mmW2=W_Zo mmW3=W_Zo_trans mm

MLINID=TL8W=W_Zo_trans mmL=L_Zo_trans mm

MLINID=TL9W=W_Zosrt2_trans mmL=L_Zosrt2_trans mm

12

3

MTEEID=TL10W1=W_Zo mmW2=W_Zosrt2_trans mmW3=W_Zo_trans mm

MLINID=TL11W=W_Zo_trans mmL=L_Zo_trans mm



STACKUPName=SUB2


PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

PORTP=3Z=50 Ohm

PORTP=4Z=50 Ohm

W_Zo = 2.95984L_Zo = 10W_Zo_trans = 2.95984

L_Zo_trans=15.1

W_Zosrt2_trans = 5.07209L_Zosrt2_trans=13.55

W

W

1

2

3

4

MCLINID=TL4W=Wd mmS=Sep mmL=L mm

MCURVEID=TL3W=Wd mmANG=90 DegR=Ra mm




MLINID=TL1W=Wd mmL=L_feed mm





STACKUPName=SUB2


PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

PORTP=3Z=50 Ohm

PORTP=4Z=50 Ohm

L_feed = 12

Ra = Wd/2

Wd=4.624384765625

L=24.0056840820313

Sep=1.84562629699707

5



Performance:


Figure 20: Coupling, insertion and return losses

Figure 21: Phase measurement


Figure 22: Comparison of coupling


Figure 24: Comparison of phase difference

v. Microstrip Filters

Objective:

Design a Chebychev 0.5dB ripple low pass filter and

a Butterworth low pass filter using microstrip lines.

1 2 3 4 5

Frequency (GHz)

Measurements

-40

-30

-20

-10

0

DB(|S(1,1)|)3 dB Quadrature Coupler








1 2 3 4 5

Frequency (GHz)

Relative Phase

0

50

100

150

200

2.5 GHz89.78 Deg

SDeltaP(3 dB Quadrature Coupler,2,1,3,1) (Deg)3 dB Quadrature Coupler

1 2 3 4 5

Frequency (GHz)

Comparison Coupled Port

-40

-35

-30

-25

-20

-15

-10

2.369 GHz-19.2 dB

3.02 GHz-19.01 dB

2.369 GHz-19.17 dB

1.84 GHz-18.93 dB

2.5 GHz-19.24 dB

2.5 GHz-19.1 dB

DB(|S(3,1)|)Edge Coupled AXIEM

DB(|S(2,1)|)P1TOP3

1 2 3 4 5

Frequency (GHz)

Comparison Input Return Loss at Port 1

-80

-60

-40

-20

0

2.5 GHz-41.8 dB

2.5 GHz-22.42 dB

2.9 GHz-36.07 dB

2.395 GHz-44.48 dB

DB(|S(1,1)|)P1TOP3

DB(|S(1,1)|)Edge Coupled AXIEM

1 2 3 4 5

Frequency (GHz)

Comparison Phase Difference

-100

-50

0

50

100

2.369 GHz-86.2 Deg

2.369 GHz-84.65 Deg

2.5 GHz-85.88 Deg

2.5 GHz-84.8 Deg

SDeltaP(Edge Coupled AXIEM,2,1,3,1) (Deg)Edge Coupled AXIEM

SDeltaP(P1TOP3,2,1,2,1) (Deg)P1TOP2

6

Design Goal:

Chebychev:


Center Frequency, fc (GHz) 2.5

Ripple (dB) 0.5

Insertion Loss at 5GHz (2fc) (dB) >40 Table 6: Design parameters

Butterworth:


Center Frequency, fc (GHz) 2.5

Insertion Loss at 5GHz (2fc) (dB) >40 Table 7: Design parameters

Design:

Chebychev:


Figure 26: 2D mesh layout


Butterworth:


Figure 29: 2D mesh layout


Performance:

Chebychev:

Figure 31: Comparison of return loss at port 1









MSTEP$ID=TL2

MSTEP$ID=TL10


1 2

3


1 2

3


STACKUPName=SUB2

EXTRACTID=EX1EM_Doc="EM_Extract_Doc"Name="EM_Extract"Simulator=AXIEMX_Cell_Size=1 mmY_Cell_Size=1 mmSTACKUP=""Override_Options=YesHierarchy=OffSweepVar_Names=""PORT

P=1Z=50 Ohm

PORTP=2Z=50 Ohm

21

MLINID=TL6W=Wzh mmL=L_2 mmMSUB=SUB1

MLINID=TL7W=Wzl mmL=C_1 mmMSUB=SUB1







PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

Zh = 80

Zl = 20Wzl = 16.1814

C_1 = 2.37832L_2 = 11.0609C_3 = 10.2292L_4 = 17.8139

Wzh = 2.20076

2 1

0.1 2.1 4.1 6.1 8

Frequency (GHz)

Chebychev Filter Comparison

-60

-40

-20

0

20

DB(|S(1,1)|)CP1TOP2

DB(|S(1,1)|)AXIEM

0.1 2.1 4.1 6.1 8

Frequency (GHz)


-60

-40

-20

0

20

DB(|S(2,2)|)CP1TOP2

DB(|S(2,2)|)AXIEM

7


Figure 34: Ripples in the passband

Butterworth:




vi. Microwave Amplifier

Objective:

Design a microwave RF amplifier using NEC32584C

transistor. To satisfy design, microstrip input and

output matching networks and a quarter

wavelength transformer need to be designed as

well. A feedback loop is to be designed using a

series capacitor and resistor.

Design Goals:


Frequency Range (GHz) 0.7 – 1.0

Liner Gain (dB) >8

Gain Flatness across band (dB) <1.0


Output Return Loss (dB) >15

VD (volts) 2

IDS (mA) 10

k-Factor (over 0.5-3GHz) >1 Table 8: Design requirements

0.1 2.1 4.1 6.1 8

Frequency (GHz)


-60

-50

-40

-30

-20

-10

0

2.361 GHz-1.338 dB

2.569 GHz-1.24 dB

5 GHz-42.04 dB

5.138 GHz-48.11 dB

5 GHz-50 dB

4.722 GHz-42.11 dB

DB(|S(2,1)|)CP1TOP2

DB(|S(2,1)|)AXIEM

0.1 2.1 4.1 6.1 8

Frequency (GHz)


-2

-1.5

-1

-0.5

0

0.1 GHz-0.07592 dB

2.19 GHz-0.8422 dB

2.423 GHz-0.738 dB

1.94 GHz-1.043 dB

2.083 GHz-0.9812 dB

1.27 GHz-0.3516 dB

1.275 GHz-0.2913 dB

0.7343 GHz-0.5429 dB

0.73 GHz-0.5782 dB

2.361 GHz-1.338 dB

2.569 GHz-1.24 dB

DB(|S(2,1)|)CP1TOP2

DB(|S(2,1)|)AXIEM

0.1 2.1 4.1 6.1 8

Frequency (GHz)

Butterworth Filter Comparison

-60

-50

-40

-30

-20

-10

0

DB(|S(1,1)|)BP1TOP2

DB(|S(1,1)|)AXIEM

0.1 2.1 4.1 6.1 8

Frequency (GHz)


-60

-50

-40

-30

-20

-10

0

DB(|S(2,2)|)BP1TOP2

DB(|S(2,2)|)AXIEM

0.1 2.1 4.1 6.1 8

Frequency (GHz)


-40

-30

-20

-10

0

5 GHz-25.21 dB

4.384 GHz-28.15 dB

2.192 GHz-3.104 dB

5 GHz-19.64 dB

2.051 GHz-3.039 dB

4.102 GHz-26.25 dB

DB(|S(2,1)|)BP1TOP2

DB(|S(2,1)|)AXIEM

8

Design:

Figure 38:Circuit layout



Performance:

Figure 41: Comparison of achievable gain


Figure 43: Comparison of output return loss

Figure 44: Comparison of stability (K-Factor)

vii. MMIC Filters on GaAs Substrate

Objective:

Design two MMIC Butterworth filters (low-pass and

high-pass) on GaAs substrate with a center

frequency of 5GHz while achieving maximum figure

CAPID=C1C=4.7e-5 uF

MBENDAID=TL10W=1.09176 mmANG=90 DegMSUB=SUB1




MLINID=TL2W=2.95758 mmL=10 mmMSUB=SUB1



MLINID=TL11W=1.09176 mmL=len mmMSUB=SUB1


MLINID=TL15W=1.09176 mmL=len mmMSUB=SUB1


MSTEPID=TL3W1=1.09176 mmW2=2.95758 mmMSUB=SUB1


RESID=R1R=250 Ohm

RESID=R2R=250 Ohm

1 2

3

SUBCKTID=S1NET="lab8v2"

PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

len=6

100 3100 6100 8500

Frequency (MHz)

Gain Comparison

-20

-15

-10

-5

0

5

10

1000 MHz700 MHz

850 MHz5.228 dB

850 MHz9.51 dB

DB(|S(2,1)|)Lab8

DB(|S(2,1)|)AMPSS_PARAMETERS02

100 3100 6100 8500

Frequency (MHz)

Comparison of Input Return Loss

-50

-40

-30

-20

-10

0

1000 MHz700 MHz

1220 MHz-5.996 dB

2168 MHz-3.072 dB

DB(|S(1,1)|)Lab8


100 3100 6100 8500

Frequency (MHz)

Comparison of Output Return Loss

-50

-40

-30

-20

-10

0

1000 MHz700 MHz

610 MHz-11.6 dB

2890 MHz-4.442 dB

DB(|S(2,2)|)Lab8


100 3100 6100 8500

Frequency (MHz)

Comparison of Stability

-10

10

30

50

70

90

110

120

K()Lab8

K()AMPSS_PARAMETERS02

9

of merit (small size and high rejection at 2fc) for

both designs.

Design Goals:


Cutoff Frequency (GHz) 5.0

Rejection at 2fc for low pass (dB) >25

Rejection at 0.5fc for high pass (dB) >25

Size Minimum

Cost Minimum

Figure of Merit, M Maximum Table 9: Design goals for both filters

Design:

Low-pass Filter:



High-pass Filter:



Performance:

Low-pass Filter:

Figure 49: Insertion and return losses

High-pass Filter:

Figure 50: Insertion and return losses

- END -

MSUBEr=12.9H=150 umT=2 umRho=1Tand=0.0005ErNom=12.9Name=SUB1

TFC2ID=TFC1W=width umL=len umT=0.2 umER=6.8RHO=1TAND=0MSUB=SUB1

TFC2ID=TFC2W=width umL=len umT=0.2 umER=6.8RHO=1TAND=0MSUB=SUB1

12

3


MVIA1PID=V1D=60 umH=150 umT=2 umW=100 umRHO=1MSUB=SUB1

12

3



MLINID=TL3W=12.5 umL=100 umMSUB=SUB1

MLINID=TL4W=width umL=10 umMSUB=SUB1



MLINID=TL7W=width umL=10 umMSUB=SUB1


MLINID=TL9W=100 umL=100 umMSUB=SUB1


MCINDSID=MSP1NT=2.93W=12.5 umS=7.24 umR=20.5 umAB=0WB=10 umHB=2.06 umLB=0 umEPSB=1TDB=0TB=1.05 umRhoB=1MSUB=SUB1




MCURVE$ID=TL11ANG=90 DegR=10 umMSUB=SUB1

MCURVE$ID=TL13ANG=-90 DegR=50 umMSUB=SUB1

MSTEP$ID=TL15MSUB=SUB1








MCURVE$ID=TL22ANG=-90 DegR=10 umMSUB=SUB1




PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

len=59.79

width=54.99

MCINDSID=MSP1NT=3.55W=42.5 umS=6.63 umR=16.2 umAB=0WB=11.3 umHB=2.18 umLB=0 umEPSB=1TDB=0TB=12.5 umRhoB=1


1 2

3

MTEE$ID=TL1

TFC2ID=TFC1W=w umL=l umT=0.2 umER=6.8RHO=1TAND=0

MCINDSID=MSP2NT=2.25W=42.9 umS=7.08 umR=17.4 umAB=0WB=11.3 umHB=2.21 umLB=0 umEPSB=1TDB=0TB=12.5 umRhoB=1


TFC2ID=TFC2W=w umL=l umT=0.2 umER=6.8RHO=1TAND=0

1 2

3

MTEE$ID=TL2

1 2

3

MTEE$ID=TL3

MCINDSID=MSP3NT=3.55W=42.5 umS=6.63 umR=16.2 umAB=0WB=11.3 umHB=2.18 umLB=0 umEPSB=1TDB=0TB=12.5 umRhoB=1MVIA1P

ID=V3D=60 umH=150 umT=2 umW=65 umRHO=1MSUB=SUB1

MLINID=TL4W=w umL=10 um

MLINID=TL5W=w umL=10 um

MSUBEr=12.9H=150 umT=2 umRho=1Tand=0.0005ErNom=12.9Name=SUB1

MLINID=TL6W=w umL=200 umMSUB=SUB1




MLINID=TL10W=12.5 umL=108.827 umMSUB=SUB1











MVIA1PID=V4D=60 umH=150 umT=2 umW=wv umRHO=1MSUB=SUB1




PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

w=33.95

l=32.95

wv = 100

0.1 5.1 10.1 15

Frequency (GHz)

Low Pass Filter

-60

-50

-40

-30

-20

-10

0

0.1 GHz-0.4531 dB

5 GHz-3.641 dB

10 GHz-33.98 dB

DB(|S(2,1)|)LPF

DB(|S(1,1)|)LPF

0.1 5.1 10.1 15

Frequency (GHz)

High Pass Filter

-200

-150

-100

-50

0

12.65 GHz-0.2404 dB

2.5 GHz-33.58 dB

5 GHz-3.246 dB

DB(|S(2,1)|)HPF

DB(|S(1,1)|)HPF

rf lab summary

Documents