M.Sc Thesis

M.Sc StudentSulkin Alex
SubjectA Single-Ended Unilateralization and Neutralization
Technique for Microwave/mm-Wave Integrated
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROF. Dan Ritter
Full Thesis textFull thesis text - English Version


In this thesis we study high performance and high speed Indium Phosphate Double Hetero-Junction Bipolar transistors and circuits. Due to the extremely high frequencies of operation the behavior of the transistors (and circuits) is complex and requires in-depth analysis. Therefore, the first part of the thesis focuses on the research of the electrical properties of the high speed transistor, including both static and high frequency measurements, as well as small signal and large signal characterization; as a result, non-parasitic and parasitic elements of the physical structure of the transistor are extracted. The gathered data is used to construct a high frequency and large signal model, which was validated over a wide range of operating conditions. The second part of the research thesis consists of designing of high frequency amplifiers using the resulted transistor model. During the design of the amplifiers an extensive use of full Electro - Magnetic (2.5D) simulations was made. The full structure of the surrounding passive elements (inductors, capacitors, transmission lines and interconnects) was simulated and characterized.  Two types of amplifiers were designed, the first, a standard common-emitter amplifier that consists of input and output matching and a single finger transistor. The second amplifier also consists of input and output matching networks and a single finger transistor in common emitter configuration (both amplifiers are matched for maximum available gain). In addition, the second amplifier contains a passive network which consists of mutually coupled inductors; the coupling is both a magnetic and an electrical one, achieved by a parasitic coupling inductance and a parasitic coupling capacitance. Therefore, the second amplifier is also referred to as "neutralized amplifier". The theory of neutralization states that the neutralized amplifier will show a higher (stable) gain around the frequency of interest (which was chosen to be 60GHz in our case), compared to its standard (non-neutralized) counterpart. This behavior was indeed confirmed by simulations of both amplifiers. A test chip was fabricated containing both amplifiers and scattering parameters (up to 67GHz) were measured using a high frequency measurement setup. The intrinsic gain of both amplifiers was extracted and compared. It was shown that the neutralized amplifier posses a substantially higher gain around 60GHz than the non-neutralized amplifier. The results of this research demonstrate that the proposed single-ended neutralization/unilateralization technique may be successfully employed to high frequency amplifiers in order to achieve higher gain, which is crucial in mm-Wave/Microwave integrated circuits and systems.