Bi-Directional Vector Variable Gain Amplifier for an X-Band Phased Array Radar Application

271 Pages·2016·11.91 MB·English

University of Massachusetts Amherst
ScholarWorks@UMass Amherst
Masters Theses 1911 - February 2014
2014
Bi-Directional Vector Variable Gain Amplifier for
an X-Band Phased Array Radar Application
Arash Mashayekhi
University of Massachusetts Amherst
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BI-DIRECTIONAL VECTOR VARIABLE GAIN AMPLIFIER FOR AN X-BAND
PHASED ARRAY RADAR APPLICATION

A Thesis Presented

by

ARASH MASHAYEKHI

Submitted to the Graduate School of the
University of Massachusetts Amherst in partial fulfillment
of the requirements for the degree of

MASTER OF SCIENCE IN ELECTRICAL AND COMPUTER ENGINEERING

February 2014

Department of Electrical and Computer Engineering
© Copyright by Arash Mashayekhi 2014

All Rights Reserved
BI-DIRECTIONAL VECTOR VARIABLE GAIN AMPLIFIER FOR AN X-BAND
PHASED ARRAY RADAR APPLICATION

A Thesis Presented

by

ARASH MASHAYEKHI

Approved as to style and content by:

_______________________________________
Robert Jackson, Chair

_______________________________________
Sigfrid Yngvesson, Member

_______________________________________
Christopher Salthouse, Member

____________________________________________
C. Hollot, Department Head
Department of Electrical and Computer Engineerin
ACKNOWLEDGEMENTS

I would like to express my special gratitude and thanks to my adviser Professor
Robert Jackson for providing me with an exciting and challenging research opportunity.
Professor Jackson’s patience, continuous support, and meticulous attention to detail
helped me tremendously to learn and grow while completing this work.
I would like to thank my committee members, Professor Sigfrid Yngvesson and
Professor Christopher Salthouse for their thorough review of this work and for their
invaluable comments and suggestions.
Special thanks are due to Raytheon for supporting the larger effort to which this
project is a part of, and to IBM, which generously provided the wafer space on which this
project was fabricated.
I’d like to thank my labmate and friend, Ryan Johnson, who helped with setting
up the simulation software and testing equipment.
Lastly, I would like to thank my parents for providing me with their support,
encouragement, and love for many years including throughout this process. This work
would not have been possible without them.

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ABSTRACT
BI-DIRECTIONAL VECTOR VARIABLE GAIN AMPLIFIER FOR AN X-BAND
PHASED ARRAY RADAR APPLICATION

FEBRUARY 2014

ARASH MASHAYEKHI, B.S, UNIVERSITY OF MASSACHUSETTS AMHERST

M.S.E.C.E., UNIVERSITY OF MASSACHUSETTS AMHERST

Directed by: Professor Robert Jackson

This thesis presents the design, layout, and measurements of a bi-directional
amplifier with variable vector (in-phase / quadrature) gain control that will be part of an
electronically steered phased array system. The electronically steered phased array has
many advantages over the conventional mechanically steered antennas including rapid
scanning of the beam and adaptively creating nulls in desired locations. The 10-bit bi-
directional Vector Variable Gain Amplifier (VVGA) is part of the transmit and receive
module of each antenna element where transmit and receive functionality is determined
through a simple switch. The VVGA performs amplification of the IF IQ pair by an
adjustable complex coefficient. At receive, the VVGA functions as a Vector Variable
Gain Current Amplifier (VVGCA) and at transmit, the VVGA functions as a Vector
Variable Gain Transadmittance Amplifier (VVGTA). Design procedure, layout entry,
schematic and parasitic extracted simulation results, and measurements are presented in
this thesis.
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TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS ............................................................................................... iv
ABSTRACT .........................................................................................................................v
CHAPTER
1. INTRODUCTION ...........................................................................................................1
1.1 Motivation and System Overview .....................................................................1
1.2 Vector Variable Gain Amplifier (VVGA) .........................................................4
1.3 Literature Review...............................................................................................8
1.3.1 Linear Region Multipliers ..........................................................9
1.3.2 Saturation Region Multipliers ..................................................11
1.3.3 Summary ..................................................................................13
1.4 Thesis Structure ...............................................................................................16
2. VARIABLE GAIN AMPLIFIER ..................................................................................18
2.1 System Block Diagram ....................................................................................18
2.2 VGCA ..............................................................................................................18
2.2.1 Digital Control of Current Gain ...............................................21
2.2.2 Input Impedance.......................................................................23
2.2.3 Output Impedance ....................................................................25
2.2.4 Equivalent Circuit ....................................................................26
2.2.5 CMFB ......................................................................................29
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2.2.6 DC Biasing ...............................................................................33
2.2.7 NMOS Second Order Effects ...................................................35
2.3 VGCA Schematic Simulation Results .............................................................37
2.3.1 Input Impedance.......................................................................37
2.3.2 Output Impedance ....................................................................39
2.3.3 Current Gain.............................................................................43
2.3.4 NF ............................................................................................44
2.4 VGTA ..............................................................................................................45
2.4.1 Digital Control of Transadmittance .........................................47
2.4.2 Input Impedance.......................................................................50
2.4.3 Output Impedance ....................................................................51
2.4.4 Equivalent Circuit ....................................................................52
2.4.5 CMFB ......................................................................................53
2.4.6 DC Biasing ...............................................................................56
2.4.7 PMOS Second Order Effects ...................................................57
2.5 VGTA Schematic Simulation Results .............................................................59
2.5.1 Input Impedance.......................................................................59
2.5.2 Output Impedance ....................................................................61
2.5.3 Transadmittance .......................................................................64
2.5.4 NF ............................................................................................67
3. BI-DIRECTIONAL VGA ..............................................................................................69
3.1 System Block Diagram ....................................................................................69
3.2 Bi-directional VGA: VGCA ...............................................................70
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3.3 Bi-directional VGA: VGCA Schematic Simulation Results ...........................71
3.3.1 DC ............................................................................................71
3.3.2 Input Impedance.......................................................................72
3.3.3 Output Impedance ....................................................................72
3.3.4 Current Gain.............................................................................73
3.3.5 Linearity ...................................................................................74
3.3.6 NF ............................................................................................75
3.4 Bi-directional VGA: VGTA ............................................................................77
3.5 Bi-Directional VGA: VGTA Schematic Simulation Results ..........................78
3.5.1 DC ............................................................................................78
3.5.2 Input Impedance.......................................................................79
3.5.3 Output Impedance ....................................................................82
3.5.4 Transadmittance .......................................................................84
3.5.5 Linearity ...................................................................................85
3.5.6 NF ............................................................................................86
4. BI-DIRECTIONAL VVGA ...........................................................................................88
4.1 VGA Configuration at Receive and Transmit Modes......................................89
4.2 VVGCA ...........................................................................................................94
4.2.1 Complex Current Gain .............................................................96
4.2.2 Phase Resolution ....................................................................103
4.2.3 Gain Resolution .....................................................................104
4.2.4 Linearity .................................................................................106
4.2.5 NF ..........................................................................................107
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4.3 VVGTA..........................................................................................................108
4.3.1 Complex Transadmittance .....................................................109
4.3.2 Phase Resolution ....................................................................116
4.3.3 Gain Resolution .....................................................................117
4.3.4 Linearity .................................................................................119
4.3.5 NF ..........................................................................................119
5. PHYSICAL LAYOUT AND POST-LAYOUT SIMULATIONS ..............................121
5.1 VGA Layout...................................................................................................123
5.2 VVGA Layout ................................................................................................128
5.3 Full Chip Layout ............................................................................................130
5.4 Schematic vs. Parasitic Extracted Simulation Results ...................................131
5.4.1 VGCA ....................................................................................131
5.4.2 VGTA ....................................................................................141
5.4.3 VVGCA .................................................................................150
5.4.4 VVGTA..................................................................................157
6. POST-FABRICATION MEASUREMENTS ..............................................................163
6.1 VGA: Measurements and Setup.....................................................................166
6.2 VGCA Measurements Results .......................................................................168
6.2.1 DC ..........................................................................................168
6.2.2 AC ..........................................................................................173
6.2.3 Linearity .................................................................................177
6.2.4 NF ..........................................................................................178
6.3 VGTA Measurement Results .........................................................................182
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