Spectrum analyzers are critically important tools with applications in engineering, science, and medicine. Despite substantial technological improvements, current real time spectrum analyzers for demanding applications, such as pulsed radar signal analysis, cognitive radio, and analysis of frequency hopping signals, are exceedingly complex and/or computationally expensive. This dissertation proposes to overcome these challenges by using a rapidly tuned spin torque nano-oscillator (STNO) to perform fast, broadband spectrum analysis.
STNOs are suitable for spectrum analysis for several reasons. They are nano-sized low power auto-oscillators whose microwave frequency can be easily tuned by a bias DC current. They have a small time constant due to a small intrinsic capacitance and a small intrinsic inductance, and thus can be tuned very rapidly. STNOs have typical cross sectional area between 100 and 800 nm2 , can have a tunable bandwidth as high as 10 GHz, an operation frequency from about 100 MHz to above 65 GHz, and a linear scan rate that can be over 2 GHz/ns [1, 2, 3, 4, 5]. Taken together, the characteristics of small size, high tuning speed, and high frequency, STNO based spectrum analyzers have the potential to transform spectrum analyzer technology.
By using an STNO, spectrum analysis can be performed with scanning rates and scanning bandwidths that are on par with the current state of the art, all while remaining sensitive to signals with power levels as low as the Johnson-Nyquist thermal noise floor. Specifically, this dissertation aims to show that with an STNO, spectrum analysis can be performed with a bandwidth as high as 10 GHz, a scan rate fast as 5 GHz/ns, and a maximum frequency that can exceed 65 GHz.
Additionally, this dissertation aims to shows that it is possible to perform spectrum analysis on signals with frequencies between 100 GHz and 2 THz with a spintronic device called an antiferromagnetic tunnel junction (ATJ), with a scan rate faster than 105 GHz/ns. As ATJs are also nano-sized, low power, and easily tunable elements, they have the potential to revolutionize electronics in the THz gap.
This work is primarily theoretical, showing by theory and numerical simulation, that STNOs and ATJs can perform spectrum analysis quickly on low power signals with both high fidelity and high frequency resolution. Additionally, the validity of this work has been confirmed in collaboration with experimental scientists. Results of these experiments are presented in this dissertation.
We believe that a STNO based wide-band fast spectrum analyzer will find numerous applications in microwave signal processing, telecommunications, and novel logic devices. In particular, we suggest that it can be useful for several specific applications, including cognitive radio, analysis of frequency hopping signals, and determination of pulsed radar frequencies.
|Commitee:||Tyberkevych, Vasyl, Aloi, Daniel, Wang, Xia|
|School Location:||United States -- Michigan|
|Source:||DAI-A 82/5(E), Dissertation Abstracts International|
|Subjects:||Electrical engineering, Condensed matter physics, Technical Communication, Information Technology, Computer science, Nanotechnology|
|Keywords:||ATJ, Real-time, Spectrum analysis, Spin torque, STNO, THz, Broadband spectrum , Nano-oscillator|
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