The purpose of this thesis is to design and implement an active noise cancellation headphone (ANC) with a feedback controller optimally designed using the linear quadratic regulator (LQR) design approach. The controller compares the audio input signal with the measured signal from a mini microphone in the headphone, and attempts to generate a control signal so that the headphone may reproduce a clean, low noise audio sound, without being interfered by the environmental noise. The control bandwidth of the ANC headphone is 100~600Hz. The controller design emphasizes the choice of a weighting function in shaping the controller gain at different frequencies, so as to achieve maximum in-band noise cancellation and low noise amplification outside the bandwidth. The experimental result shows achievable noise cancellation of maximum 25dB within the control bandwidth and a barely noticeable slight noise amplification of maximum 6dB at high frequencies and 4.5dB at inaudible low frequencies.

This thesis presents a feedback design for an active noise cancellation (ANC) headphone. The designed ANC headphone consists of an analog controller, an audio power amplifier, a headphone speaker, a mini microphone, and a microphone amplifier, which constitute a feedback loop. The controller design follows the method of feedback sensitivity shaping with degree constraint introduced by R. Nagamune and A. Blomqvist in 2005. The advantage of this method is that it eliminates the needs for choosing an analytic weighting function and performing model reduction to yield a lower-order controller, as commonly required in conventional H2/H¡Û optimizations. A fifth-order analog controller for the ANC headphone is designed. The experimental result shows a maximum acoustic noise reduction of 19.7 dB near 200 Hz and an overall noise reduction of more than 10 dB in the control frequency band from 107 Hz to 523 Hz. Moreover, the out-of-band noise amplification is limited to a barely noticeable level of 4.26 dB.

The aim of this thesis is to design an amplifier for electrostatic and dynamic headphones with D/A converter integrated into one device. This device is controlled by a microcontroller The thesis deals mainly with the design, realisation and testing of all functional blocks of the device.

The design of a battery-powered, portable headphone active noise control system with TI TMS320C5416 DSP is described. The preliminary implementation of the system on a C5416 DSK is also explained. The problems of fixed-point implementation are described and solutions are proposed. Sign-sign Fx-LMS algorithm with a dead-zone is introduced and used as the adaptation algorithm. Effective use of dynamic range to improve the accuracy in filtering operations is discussed. Details of the designed battery-powered DSP board are given and board software development process is explained. The DSK system and designed portable system is compared against two commercially available analog systems under three different types of noises / composition of tones, drill noise and propeller plane cabin noise. The results reveal that adaptive system has better overall performance.

This thesis deals with design and development of a I2S module driver for real-time operating system MQX running on a ColdFire V4 architecture based processor. Further there are presented circuit diagrams and PCBs created for testing of functions and properties of the driver. Signal input is a digital audio in form of S/PDIF interface, output is an analogue signal, that can be listened by the means of a headphone amplifier. The conclusion describes a sample application demonstrating function of the driver on developed hardware.

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We have all read about the rapid development of today’s business landscape as well as the increase in globalization. Companies are forced to operate in new ways in order to stay competitive. At the same time, globalization has opened up new business opportunities for companies. This has lead to the emergence of born global companies, which carry out rapid internationalization processes from an early stage, and challenge traditional internationalization models such as the Uppsala model. According to existing literature, there are several challenges with adopting a born global strategy, and international entrepreneurship orientation becomes an important aspect in order to succeed. Finding a balance between innovativeness, risk-taking, and proactiveness is the key in order for born global companies to succeed in their internationalization process. This study investigates how international entrepreneurship orientation affects the internationalization process of born global companies in Sweden. I have, with the help of a qualitative study, looked into how Swedish SME born global companies in the ear-and headphone industry have managed to take on several international markets in their internationalization process and in what way international entrepreneurship orientation in combination with other factors have played a crucial role. / Vi har alla läst om den snabba utvecklingen av dagens affärslandskap samt den ökade globaliseringen. Företag tvingas idag att hitta nya sätt att arbeta på för att förbli konkurrenskraftiga. Globalisering har i sin tur skapat nya möjligheter för företag, vilket har lett till uppkomsten av born global-företag. Dessa företag karaktäriseras av att genomföra snabba internationaliseringsprocesser från ett tidigt skede och utmanar på så sätt mer traditionella modeller så som Uppsalamodellen. Enligt existerande litteratur finns det ett flertal utmaningar när det kommer till att ta sig an en born global-strategi och internationell entreprenörskapsorientering blir därmed en viktig aspekt för att lyckas. Att hitta en balans mellan innovativitet, proaktivitet och risktagande är nyckeln för att ett born globalföretag ska lyckas i sin internationaliseringsprocess. Den här studien undersöker hur internationell entreprenörskapsorientering påverkar internationaliseringsprocessen hos born global-företag i Sverige. Jag har med hjälp av en kvalitativ studie undersökt hur svenska SME born global-företag inom hörlursbranschen har lyckats ta sig an flera internationella marknader i deras internationaliseringsprocess och på vilket sätt internationell entreprenörskapsorientering i kombination med andra faktorer har haft en kritisk roll i processen.

Three main analog circuit building blocks that are important for a mixed-signal system are investigated in this work. New building blocks with emphasis on power efficiency and compatibility with deep-submicron technology are proposed and experimental results from prototype integrated circuits are presented. Firstly, a 1.1GHz, 5th order, active-LC, Butterworth wideband equalizer that controls inter-symbol interference and provides anti-alias filtering for the subsequent analog to digital converter is presented. The equalizer design is based on a new series LC resonator biquad whose power efficiency is analytically shown to be better than a conventional Gm-C biquad. A prototype equalizer is fabricated in a standard 0.18μm CMOS technology. It is experimentally verified to achieve an equalization gain programmable over a 0-23dB range, 47dB SNR and -48dB IM3 while consuming 72mW of power. This corresponds to more than 7 times improvement in power efficiency over conventional Gm-C equalizers. Secondly, a load capacitance aware compensation for 3-stage amplifiers is presented. A class-AB 16W headphone driver designed using this scheme in 130nm technology is experimentally shown to handle 1pF to 22nF capacitive load while consuming as low as 1.2mW of quiescent power. It can deliver a maximum RMS power of 20mW to the load with -84.8dB THD and 92dB peak SNR, and it occupies a small area of 0.1mm2. The power consumption is reduced by about 10 times compared to drivers that can support such a wide range of capacitive loads. Thirdly, a novel approach to design of ADC in deep-submicron technology is described. The presented technique enables the usage of time-to-digital converter (TDC) in a delta-sigma modulator in a manner that takes advantage of its high timing precision while noise-shaping the error due to its limited time resolution. A prototype ADC designed based on this deep-submicron technology friendly architecture was fabricated in a 65nm digital CMOS technology. The ADC is experimentally shown to achieve 68dB dynamic range in 20MHz signal bandwidth while consuming 10.5mW of power. It is projected to reduce power and improve speed with technology scaling.