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 Follow this and additional works at:https://scholarworks.umass.edu/theses Part of theControls and Control Theory Commons,Electrical and Electronics Commons, Electronic Devices and Semiconductor Manufacturing Commons, and theVLSI and Circuits, Embedded and Hardware Systems Commons Mashayekhi, Arash, "Bi-Directional Vector Variable Gain Amplifier for an X-Band Phased Array Radar Application" (2014).Masters Theses 1911 - February 2014. 1190. Retrieved fromhttps://scholarworks.umass.edu/theses/1190 This thesis is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Masters Theses 1911 - February 2014 by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. 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. iv 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. v 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 vi 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 vii 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 viii 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 ix
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