Mina anesh

Master of Applied Science (Electrical Engineering)

Contact: mina@waves.toronto.edu

Master thesis research (Thesis Supervisor: Dr. John R. Long)

"Monolithic Inductors for Silicon Radio Frequency Integrated Circuits"

ABSTRACT

A novel parameter extraction technique is applied to the modeling of rectangular spiral inductors and validated with measurements and simulations. To enhance the inductor quality (Q) factor, a differentially excited symmetric inductor is used. Compared with a single-ended configuration, the differential structure offers a higher Q-factor over a wider range of frequencies. Application of the symmetric inductor model is demonstrated using two oscillator designs in which a differentially excited symmetric inductor is compared with conventional spiral inductors. The symmetric inductor improves the overall circuit performance and saves chip area.

Thesis and publications on monolithic inductors

Master Thesis Thesis Presentation Slides	Publications Conference Presentation Slides
Brief Literature Survey	More Sites

What are monolithic inductors?

Monolithic inductors and transformers are used in all stages of RF circuits, such as amplifiers, mixers and oscillators. Actual configurations of inductors consist of a single microstrip line with a high characteristic impedance, a continuous square wave shape microstrip line, called the meander inductor, and the circular shaped line with possibly several turns depending on the inductor’s equivalent value. The latter provides higher inductance values and is commonly used, however, because of fabrication precision restrictions, the circular shape is implemented as a rectangular spiral. Mutual coupling between lines provides mutual inductances in addition to the self-inductance of a single transmission line, thus increasing its overall impedance value. Inductor lumped element equivalent circuit models are defined by the quasi-TEM transmission mode model, which considers the losses due to the silicon and the silicon dioxide insulator substrates, the conductor metal characteristics and mutual coupling between the coupled lines. Present monolithic inductors can achieve a maximum Q-factor of 10, posing a major problem for narrowband circuits. Optimum design for a higher Q-factor consists of applying a certain thickness for the conductor metal and the insulator, and a higher substrate resistivity. Also considered is the fabrication of multilevel stacked layers of microstrip coupled lines or the removal of silicon from beneath the inductor. Moreover, these spiral structures take a fair amount of space on the chip, when compared with other components, such as transistors and resistors.

Background

Bachelor of Engineering: Electrical Engineering (1996), Concordia University

Research assistant, Concordia University (1994-1996): Cellular phones under the microscope

Research project for calculating the specific absorption rate (SAR) of electromagnetic fields in the human head, while in the presence of a cellular telephone, using the finite difference time domain (FDTD) method. Full responsibility of the project: made a three-dimensional graphic head model with cubical cells, modified the FDTD previous program for dielectric objects and near to far zone transformation, and developed a graphic version for FDTD showing the objects’ model and electric field in space. Some measurements were also done for validation at the Canadian Space Agency (David Florida Lab) in the near field for a portable handset with a box or a sphere filled with water or liquids simulating a human brain.

Research associate, École Polytechnique de Montréal (POLY-GRAMES) (Summer 1996)

Research project in Electromagnetic Compatibility for characterizing ferrite beads to suppress currents on cables in the UHF and microwave ranges. Realized different configurations with bazooka baluns on a coax cable to broaden the bandwidth of the effectiveness of current suppressions. Validation of computer simulations and measurements.

Selected Publications

M. Danesh, J.R. Long, R. Hadaway and D. Harame, "A Q-Factor Enhancement Technique for MMIC Inductors", 1998 IEEE MTT-S International Microwave Symposium, Baltimore: USA, June 7-12 1998, pp. 183-186.
C.W. Trueman, S.R. Mishra, D. Rensburg, S.J. Kubina and M. Danesh, "Validation of Computed Portable Radio Handset Near Fields by Measurement", Symposium on Antenna Technology and Applied Electromagnetics (ANTEM), Montreal: Canada, August 6-9 1996, pp. 421-431.

Abstract - This paper compares the measured and computed fields of a portable radio at 850 MHz operated adjacent to a simple representation of the head, either a box or a sphere. The measurement uses an aluminum box for a handset, with a quarter-wave monopole antenna. The box or sphere representing the head is a thin plexiglas shell filled with liquid having the electrical properties of the human brain. The measurement setup uses a near field scanner to measure the component of the electric field over planes 50 by 50 cm in size. The computation uses the finite-difference time-domain method, with a sinusoidal generator at the base of the monopole and time-stepping to steady-state. Comparing measured and computed contour maps of Ez shows good agreement for the handset alone, with "hot spots" at the base of the case, at the top of the case near the antenna feed point, and at the tip of the antenna. When the box or sphere "head" is present, reasonable agreement is obtained, and the "hot spots" remain.

C. W. Trueman, S. J. Kubina and M. Danesh, "Fields of Portable Radio Handset Near the Human Head", Final Report, Communications Research Centre, Ottawa, Technical Note TN-EMC-96-01, Electromagnetic Compatibility Laboratory, Concordia University, March 31 1996.