Zoya Popovic - Academia.edu (original) (raw)

Papers by Zoya Popovic

25th Annual Technical Digest 2003. IEEE Gallium Arsenide Integrated Circuit (GaAs IC) Symposium, 2003., 2003

The problem addressed in this paper is reduction of heat dissipation and improvement of dc power ... more The problem addressed in this paper is reduction of heat dissipation and improvement of dc power usage by increasing the power added efficiency (PAE) and drain efficiency (η) of X-band power amplifiers (PAs) to above 60% and 70%, respectively. Adaptive PAs with dynamic biasing and impedance tuning are also discussed.

This paper presents miniature broadband bias tee networks designed in a micro-coaxial environment... more This paper presents miniature broadband bias tee networks designed in a micro-coaxial environment. The process for fabricating the air-filled coaxial lines by wafer-scale sequential metal deposition, referred to as PolyStrata™, enables hybrid assembly of surface-mount components such as inductors and capacitors, enabling DC blocks and RF chokes. The microcoaxial lines can be designed with a wide variety of characteristic impedances fabricated in the same process, allowing for easier matching to active devices such as power amplifiers, which typically have low input and output impedances. In this paper, bias tee networks in both 12Ω and 50Ω environments are demonstrated with 0402 capacitors and 0402 inductors, as well as with monolithically integrated coil inductors. The measured performance shows 14 dB insertion loss from 4 to 16 GHz with a better than 0.75 dB return loss and up to 5 A power handling in a circuit with a 8.3 mm2 footprint.

2007 IEEE Antennas and Propagation Society International Symposium, 2007

SBMO/IEEE MTT-S International Conference on Microwave and Optoelectronics, 2005.

This paper addresses the design, characterization and applications of a discrete lens antenna arr... more This paper addresses the design, characterization and applications of a discrete lens antenna array (DLA). The DLA is a multibeam spatially-fed antenna array and is designed for ground stations for satellite communications as a lower-cost alternative to a phased array. The antenna beam scans from -40 degrees to +40 degrees by switching between feeds corresponding to different beams, thus tracking

IEEE Antennas and Propagation Society Symposium, 2004., 2004

ABSTRACT

2008 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems, 2008

2011 XXXth URSI General Assembly and Scientific Symposium, 2011

ABSTRACT This paper discusses broadband dispersion control at microwave frequencies using non-uni... more ABSTRACT This paper discusses broadband dispersion control at microwave frequencies using non-uniform transmission-line elements. The motivation for the work is post-dispersion in optical links for compensating fiber dispersion. The implemented designs cover a 15GHz bandwidth, over which a linearly increasing group delay from about 200 ps to 400 ps is desired. Dispersion is accomplished with non-uniform transmission lines used in both transmission and reflection modes. Finally the two architectures are compared.

2009 IEEE MTT-S International Microwave Symposium Digest, 2009

2006 European Microwave Conference, 2006

A quasi-planar 250-mum-thick Ka-band resonator is designed and fabricated using a planarized micr... more A quasi-planar 250-mum-thick Ka-band resonator is designed and fabricated using a planarized microfabrication process. An air-filled TE 101 cavity resonator is modified to include vertical posts for improved mechanical stability and a metallic capacitive loading puck to reduce the overall device footprint. This 7.5 mm by 7.5 mm footprint is roughly 15 % smaller than that of an unaltered cavity

2008 IEEE MTT-S International Microwave Symposium Digest, 2008

2006 European Microwave Conference, 2006

2006 IEEE MTT-S International Microwave Symposium Digest, 2006

A miniature non-uniform copper-air rectangular coaxial line with the inner conductor supported by... more A miniature non-uniform copper-air rectangular coaxial line with the inner conductor supported by periodic dielectric straps is demonstrated. The overall height of the line is 310mum with the outer conductor cross-section being 250mumtimes250mum. The measured loss is 0.22dB/cm at 26GHz, while the isolation between two parallel lines with a center-to-center separation of 700mum is better than 60dB. Several quasi-planar components

2007 IEEE/MTT-S International Microwave Symposium, 2007

Page 1. Linearity of X-band Class-B Power Amplifiers in a Digital Polar Transmitter Narisi Wang, ... more Page 1. Linearity of X-band Class-B Power Amplifiers in a Digital Polar Transmitter Narisi Wang, Nestor D. Lopez, Vahid Yousefzadeh, John Hoversten, Dragan Maksimovic and Zoya Popovic Department of Electrical and Computer ...

2008 33rd International Conference on Infrared, Millimeter and Terahertz Waves, 2008

An overview of components designed and implemented in the PolyStrata micro-coaxial technology at ... more An overview of components designed and implemented in the PolyStrata micro-coaxial technology at millimeter-wave frequencies will be presented. The components are designed and characterized at the University of Colorado, and fabricated by Rohm and Haas Electronics, in collaboration with BAE Systems. Micro-coaxial air-filled cables with purely TEM propagation up to 450 GHz are fabricated using sequential deposition of 5 to

2008 IEEE MTT-S International Microwave Symposium Digest, 2008

Page 1. A 65–W High–Efficiency UHF GaN Power Amplifier Néstor D. López, John Hoversten, Matthew P... more Page 1. A 65–W High–Efficiency UHF GaN Power Amplifier Néstor D. López, John Hoversten, Matthew Poulton∗ and Zoya Popovic Department of Electrical and Computer Engineering University of Colorado, Boulder, Colorado 80309, USA ...

2006 IEEE MTT-S International Microwave Symposium Digest, 2006

Page 1. 785 Class-E Power Amplifier in a Polar EDGE Transmitter Nestor D. Lopez, Xufeng Jiang, Dr... more Page 1. 785 Class-E Power Amplifier in a Polar EDGE Transmitter Nestor D. Lopez, Xufeng Jiang, Dragan Maksimovic and Zoya Popovic Department of Electrical and Computer Engineering University of Colorado, Boulder, Colorado 80309, USA ...

2009 Annual IEEE Compound Semiconductor Integrated Circuit Symposium, 2009

2008 IEEE Radio and Wireless Symposium, 2008

30th European Microwave Conference, 2000, 2000

25th Annual Technical Digest 2003. IEEE Gallium Arsenide Integrated Circuit (GaAs IC) Symposium, 2003., 2003

The problem addressed in this paper is reduction of heat dissipation and improvement of dc power ... more The problem addressed in this paper is reduction of heat dissipation and improvement of dc power usage by increasing the power added efficiency (PAE) and drain efficiency (η) of X-band power amplifiers (PAs) to above 60% and 70%, respectively. Adaptive PAs with dynamic biasing and impedance tuning are also discussed.

This paper presents miniature broadband bias tee networks designed in a micro-coaxial environment... more This paper presents miniature broadband bias tee networks designed in a micro-coaxial environment. The process for fabricating the air-filled coaxial lines by wafer-scale sequential metal deposition, referred to as PolyStrata™, enables hybrid assembly of surface-mount components such as inductors and capacitors, enabling DC blocks and RF chokes. The microcoaxial lines can be designed with a wide variety of characteristic impedances fabricated in the same process, allowing for easier matching to active devices such as power amplifiers, which typically have low input and output impedances. In this paper, bias tee networks in both 12Ω and 50Ω environments are demonstrated with 0402 capacitors and 0402 inductors, as well as with monolithically integrated coil inductors. The measured performance shows 14 dB insertion loss from 4 to 16 GHz with a better than 0.75 dB return loss and up to 5 A power handling in a circuit with a 8.3 mm2 footprint.

2007 IEEE Antennas and Propagation Society International Symposium, 2007

SBMO/IEEE MTT-S International Conference on Microwave and Optoelectronics, 2005.

This paper addresses the design, characterization and applications of a discrete lens antenna arr... more This paper addresses the design, characterization and applications of a discrete lens antenna array (DLA). The DLA is a multibeam spatially-fed antenna array and is designed for ground stations for satellite communications as a lower-cost alternative to a phased array. The antenna beam scans from -40 degrees to +40 degrees by switching between feeds corresponding to different beams, thus tracking

IEEE Antennas and Propagation Society Symposium, 2004., 2004

ABSTRACT

2008 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems, 2008

2011 XXXth URSI General Assembly and Scientific Symposium, 2011

ABSTRACT This paper discusses broadband dispersion control at microwave frequencies using non-uni... more ABSTRACT This paper discusses broadband dispersion control at microwave frequencies using non-uniform transmission-line elements. The motivation for the work is post-dispersion in optical links for compensating fiber dispersion. The implemented designs cover a 15GHz bandwidth, over which a linearly increasing group delay from about 200 ps to 400 ps is desired. Dispersion is accomplished with non-uniform transmission lines used in both transmission and reflection modes. Finally the two architectures are compared.

2009 IEEE MTT-S International Microwave Symposium Digest, 2009

2006 European Microwave Conference, 2006

A quasi-planar 250-mum-thick Ka-band resonator is designed and fabricated using a planarized micr... more A quasi-planar 250-mum-thick Ka-band resonator is designed and fabricated using a planarized microfabrication process. An air-filled TE 101 cavity resonator is modified to include vertical posts for improved mechanical stability and a metallic capacitive loading puck to reduce the overall device footprint. This 7.5 mm by 7.5 mm footprint is roughly 15 % smaller than that of an unaltered cavity

2008 IEEE MTT-S International Microwave Symposium Digest, 2008

2006 European Microwave Conference, 2006

2006 IEEE MTT-S International Microwave Symposium Digest, 2006

A miniature non-uniform copper-air rectangular coaxial line with the inner conductor supported by... more A miniature non-uniform copper-air rectangular coaxial line with the inner conductor supported by periodic dielectric straps is demonstrated. The overall height of the line is 310mum with the outer conductor cross-section being 250mumtimes250mum. The measured loss is 0.22dB/cm at 26GHz, while the isolation between two parallel lines with a center-to-center separation of 700mum is better than 60dB. Several quasi-planar components

2007 IEEE/MTT-S International Microwave Symposium, 2007

Page 1. Linearity of X-band Class-B Power Amplifiers in a Digital Polar Transmitter Narisi Wang, ... more Page 1. Linearity of X-band Class-B Power Amplifiers in a Digital Polar Transmitter Narisi Wang, Nestor D. Lopez, Vahid Yousefzadeh, John Hoversten, Dragan Maksimovic and Zoya Popovic Department of Electrical and Computer ...

2008 33rd International Conference on Infrared, Millimeter and Terahertz Waves, 2008

An overview of components designed and implemented in the PolyStrata micro-coaxial technology at ... more An overview of components designed and implemented in the PolyStrata micro-coaxial technology at millimeter-wave frequencies will be presented. The components are designed and characterized at the University of Colorado, and fabricated by Rohm and Haas Electronics, in collaboration with BAE Systems. Micro-coaxial air-filled cables with purely TEM propagation up to 450 GHz are fabricated using sequential deposition of 5 to

2008 IEEE MTT-S International Microwave Symposium Digest, 2008

Page 1. A 65–W High–Efficiency UHF GaN Power Amplifier Néstor D. López, John Hoversten, Matthew P... more Page 1. A 65–W High–Efficiency UHF GaN Power Amplifier Néstor D. López, John Hoversten, Matthew Poulton∗ and Zoya Popovic Department of Electrical and Computer Engineering University of Colorado, Boulder, Colorado 80309, USA ...

2006 IEEE MTT-S International Microwave Symposium Digest, 2006

Page 1. 785 Class-E Power Amplifier in a Polar EDGE Transmitter Nestor D. Lopez, Xufeng Jiang, Dr... more Page 1. 785 Class-E Power Amplifier in a Polar EDGE Transmitter Nestor D. Lopez, Xufeng Jiang, Dragan Maksimovic and Zoya Popovic Department of Electrical and Computer Engineering University of Colorado, Boulder, Colorado 80309, USA ...

2009 Annual IEEE Compound Semiconductor Integrated Circuit Symposium, 2009

2008 IEEE Radio and Wireless Symposium, 2008

30th European Microwave Conference, 2000, 2000