<p>This thesis studies the problems with maintaining the spectral purity of fully integrated VCO circuits for radio frequency synthesizers in single-chip system designs. LC tank circuit oscillator circuits are shown to convert amplitude variation in the tank circuit voltage into frequency modulation, if voltage dependent capacitances are present in the tank circuit. Since the parasitic capacitances of the gain transistors and the capacitance of the varactor device in a VCO circuit are voltage dependent, any interfering signal, that is able to modulate the amplitude of the VCO tank circuit voltage waveform, is converted to FM sidebands in the output signal spectrum. It is also shown that the AM-FM conversion may be prohibited under some conditons.</p><p>A new method for simulating the steady-state voltage waveform of an LC tank circuit oscillator is presented. In this method, one complete oscillation cycle is simulated piecewise, employing the known solution of the damped harmonic motion equation. The voltage-dependent parameters of the equation are updated in the beginning of each segment. The steady state is found by matching the initial conditions and the final conditions of one complete oscillation cycle, using a numerical optimization algorithm. The method avoids finding the solution of the differential equation with variable coefficients.</p><p>For minimizing the sensitivity of integrated VCO circuits to the intra-chip noise sources, this work proposes minimizing the AM-FM conversion by designing the VCO in the way that the voltage dependent capacitances of the oscillator core circuit are made to cancel each other’s effects on the oscillation frequency at some amplitude level. Experimental results demonstrate 15 dB suppression of the sidebands due to the modulated tail current noise in a negative-Gm spiral inductor PFET VCO circuit. The varactorless prototype circuit is implemented in a 0.35 µm CMOS technology. The measured tuning range of the 3 GHz back gate tuned VCO circuit is 10 %, and the current consumption of the core circuit is 2.5 mA. The phase noise level is -110 dBc at 500 kHz offset frequency.</p><p>The last part of this thesis discussses the problems with modeling and characterizing small MOS transistors, and presents characterization of 28 µm wide MOSFSET devices. A new method for extracting the drain and source electrode resistances from the measured Z22 response is presented. The response is measured at a constant and very low signal frequency, with Vds = 0 V and with various gate-source bias voltage values. At low signal frequencies, the equivalent diagram of the MOSFET is dramatically simplified, since all parasitic capacitors of the device may be ignored. Consequently, the number of degrees of freedom in the curve fitting is reduced to only two.</p>

This thesis studies the problems with maintaining the spectral purity of fully integrated VCO circuits for radio frequency synthesizers in single-chip system designs. LC tank circuit oscillator circuits are shown to convert amplitude variation in the tank circuit voltage into frequency modulation, if voltage dependent capacitances are present in the tank circuit. Since the parasitic capacitances of the gain transistors and the capacitance of the varactor device in a VCO circuit are voltage dependent, any interfering signal, that is able to modulate the amplitude of the VCO tank circuit voltage waveform, is converted to FM sidebands in the output signal spectrum. It is also shown that the AM-FM conversion may be prohibited under some conditons. A new method for simulating the steady-state voltage waveform of an LC tank circuit oscillator is presented. In this method, one complete oscillation cycle is simulated piecewise, employing the known solution of the damped harmonic motion equation. The voltage-dependent parameters of the equation are updated in the beginning of each segment. The steady state is found by matching the initial conditions and the final conditions of one complete oscillation cycle, using a numerical optimization algorithm. The method avoids finding the solution of the differential equation with variable coefficients. For minimizing the sensitivity of integrated VCO circuits to the intra-chip noise sources, this work proposes minimizing the AM-FM conversion by designing the VCO in the way that the voltage dependent capacitances of the oscillator core circuit are made to cancel each other’s effects on the oscillation frequency at some amplitude level. Experimental results demonstrate 15 dB suppression of the sidebands due to the modulated tail current noise in a negative-Gm spiral inductor PFET VCO circuit. The varactorless prototype circuit is implemented in a 0.35 µm CMOS technology. The measured tuning range of the 3 GHz back gate tuned VCO circuit is 10 %, and the current consumption of the core circuit is 2.5 mA. The phase noise level is -110 dBc at 500 kHz offset frequency. The last part of this thesis discussses the problems with modeling and characterizing small MOS transistors, and presents characterization of 28 µm wide MOSFSET devices. A new method for extracting the drain and source electrode resistances from the measured Z22 response is presented. The response is measured at a constant and very low signal frequency, with Vds = 0 V and with various gate-source bias voltage values. At low signal frequencies, the equivalent diagram of the MOSFET is dramatically simplified, since all parasitic capacitors of the device may be ignored. Consequently, the number of degrees of freedom in the curve fitting is reduced to only two.

Metallurgisk industri pr&#248;ver &#229; forene kvalitet av r&#229; varer med relativt lav pris og den beste teknologien. Eksergi gj&#248;r det mulig &#229; finne og kvantifisere evnen til forbedring av termiske og kjemiske prosesser. Selve eksergi applikasjonen har en betydelig rolle i &#229; forbedre effektivitet, dette er enn&#229; ikke vanlig i industrien.M&#229;let med denne studien er &#229; se p&#229; energi og eksergi fordeling i silisium prosessen ved Holla-anlegget. Produksjon av silisium metall er teknisk godt etablert. Kostnadsreduksjon er et nytt grep i modernifiseringen. Anlegget ved Holla har oppn&#229;dd reduserte kostnader ved &#229; bruke biligere r&#229;varer. I 2006 sluttet Holla &#229; bruke trekull i blandingen av r&#229;varer. Siden da har trekull bare v&#230;rt brukt av og til.To analyser har blitt etablert med data fra ovn #4 ved anlegget. Den f&#248;rste med data samlet inn fra 2006, der trekull var inkludert i r&#229;varen. Den andre med data fra 2001 der trekull ikke var en del av r&#229;varen.Energi analysen avdekker store energitap som g&#229;r som tapt varme. Bare 28.7 MW av 80.4 MW in den f&#248;rste analysen og 30.13 MW av 82 MW av energien ble levert til silisium-prosessen, kom tilbake som en kjemisk energi i produktet.Produksjon av silisium inneb&#230;rer store eksergi &#248;deleggelse, omtrent 39,2 MW i begge analyser.

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This project looks at the capillary systems with salt water and oil that can be found in porous stones in oil reservoir. The interactions between the different phases and how salt concentration differences can move the oil. The first problem was to find how the water migrates from one side of an oil droplet to the other due to the concentration difference. This was discussed, but not experimentally verified. The reason for this is the high inaccuracy of the experiments and the lack of knowledge before starting. However, this project gives a lot of important knowledge about the problem, and good suggestions for improvements. It was experimentally confirmed that oil is moving due to the difference in salt concentration. From this, the diffusion coefficient was found and reported to be D = (1.08 &#177; 0.10) &#183; 10&amp;#8722;7 m2/s for glass capillary tubes of radius 0,70 mm and at 60oC, calculated from the phenomenological coefficient L that was found. It was also confirmed that the capillary force does not contribute significantly for this size of the tubes, and therefore L should be independent of the radius. The maybe most interesting result of the experiments and calculations is that the capillary force will contribute significantly to the total force and then also the movement of the oil droplet. This does not happen before the radius of the tubes where under 0,20 mm. The experiments and the estimates agreed well with the radius where the change happens.