29 research outputs found
Energy-Efficient Time-Based Encoders and Digital Signal Processors in Continuous Time
Continuous-time (CT) data conversion and continuous-time digital signal processing (DSP) are an interesting alternative to conventional methods of signal conversion and processing. This alternative proposes time-based encoding that may not suffer from aliasing; shows superior spectral properties (e.g. no quantization noise floor); and enables time-based, event-driven, flexible signal processing using digital circuits, thus scaling well with technology. Despite these interesting features, this approach has so far been limited by the CT encoder, due to both its relatively poor energy efficiency and the constraints it imposes on the subsequent CT DSP. In this thesis, we present three principles that address these limitations and help improve the CT ADC/DSP system.
First, an adaptive-resolution encoding scheme that achieves first-order reconstruction with simple circuitry is proposed. It is shown that for certain signals, the scheme can significantly reduce the number of samples generated per unit of time for a given accuracy compared to schemes based on zero-order-hold reconstruction, thus promising to lead to low dynamic power dissipation at the system level.
Presented next is a novel time-based CT ADC architecture, and associated encoding scheme, that allows a compact, energy-efficient circuit implementation, and achieves first-order quantization error spectral shaping. The design of a test chip, implemented in a 0.65-V 28-nm FDSOI process, that includes this CT ADC and a 10-tap programmable FIR CT DSP to process its output is described. The system achieves 32 dB ā 42 dB SNDR over a 10 MHz ā 50 MHz bandwidth, occupies 0.093 mm2, and dissipates 15 ĀµWā163 ĀµW as the input amplitude goes from zero to full scale.
Finally, an investigation into the possibility of CT encoding using voltage-controlled oscillators is undertaken, and it leads to a CT ADC/DSP system architecture composed primarily of asynchronous digital delays. The latter makes the system highly digital and technology-scaling-friendly and, hence, is particularly attractive from the point of view of technology migration. The design of a test chip, where this delay-based CT ADC/DSP system architecture is used to implement a 16-tap programmable FIR filter, in a 1.2-V 28-nm FDSOI process, is described. Simulations show that the system will achieve a 33 dB ā 40 dB SNDR over a 600 MHz bandwidth, while dissipating 4 mW
Bezprzewodowa Jednostka Audio
Mestrado em Engenharia ElectrĆ³nicaA presente tese pretende descrever o desenvolvimento de um sistema electrĆ³nico, cuja funcionalidade se baseia na transmissĆ£o de sinais Ć”udio atravĆ©s da rede Wireless.
Inicialmente foi estudada a famĆlia de microcontroladores PIC32, no qual se incluiu a sua forma de programaĆ§Ć£o. Foi ainda realizada pesquisa acerca dos possĆveis mĆ©todos de compressĆ£o de Ć”udio, culminando com o desenvolvimento de algoritmos de compressĆ£o no software MATLAB.
Seguidamente foi desenvolvida a PIC32 Module ā daughterboard do projecto. Esta Ć© uma componente universal que contĆ©m um microcontrolador PIC32, de fĆ”cil utilizaĆ§Ć£o em outros projectos.
Posteriormente foi criado o dispositivo Wireless Audio Unit ā o objectivo basilar desta tese. Este passo compreendeu a esquematizaĆ§Ć£o e PCB de ambas as partes: o transmissor e o receptor. ApĆ³s a montagem, ambos os dispositivos forma colocados em caixas.
O firmware dos dois microcontroladores PIC32 foi criado em linguagem de programaĆ§Ć£o C. O ADC e o DAC sĆ£o controlados pelo firmware do PIC32, estando a ser executadas correctamente as suas funƧƵes.
No momento do desenvolvimento da componente escrita desta tese, ainda se mantĆŖm alguns problemas associados Ć manipulaĆ§Ć£o do transceptor. Por esta razĆ£o, o firmware WAU nĆ£o foi terminado, e o dispositivo nĆ£o cumpre, ainda, a sua funcionalidade.The thesis aims to report on the development of an electronic system, which task is to transmit wirelessly an audio signal.
The work was started by studying the PIC32 family of microcontrollers including the way of programming. The research on audio compression methods that was made, finished with development of compression algorithms in MATLAB software.
Following, the PIC32 Module ā the daughterboard of project was designed. This part is universal unit containing PIC32 microcontroller, which could be easily used in many other projects.
Afterwards, it was created the proper Wireless Audio Unit device ā the main objective of this dissertation. This step included design of schematics and PCB for two its parts: transmitter and receiver. After assembling, both devices was put into enclosures.
The firmware for two PIC32 microcontrollers was created in C programming language. The ADC and DAC are controlled by PIC32 firmware and are correctly realizing their functions.
At the moment of writing this document, the problem with handling transceiver was not solved. For this reason the firmware WAU was not finished and the device does not have its functionality.Celem niniejszego dokumentu jest opis wykonanego systemu elektronicznego, ktĆ³rego zadaniem jest bezprzewodowa transmisja sygnaÅu audio.
Praca zostaÅa rozpoczÄta od zapoznania siÄ z rodzinÄ
mikrokontrolerĆ³w PIC32, wÅÄ
czajÄ
c w to poznanie metod ich programowania. Badania nad istniejÄ
cymi metodami kompresji audio, zostaÅy uwieÅczone opracowaniem algorytmĆ³w kompresji w oprogramowaniu MATLAB.
NastÄpnie zostaÅ zaprojektowany moduÅ rozszerzenia - PIC32 Module. Jest to uniwersalna jednostka zawierajÄ
ca mikrokontroler PIC32, ktĆ³ra może byÄ Åatwo wykorzystana rĆ³wnież w innych projektach.
Kolejnym krokiem byÅo stworzenie wÅaÅciwego urzÄ
dzenia ā Wireless Audio Unit (Bezprzewodowa Jednostka Audio), bÄdÄ
cego gÅĆ³wnym celem tej pracy. Etap ten zawieraÅ projekt schematu oraz pÅytki obwodu drukowanego dwĆ³ch czÄÅci projektu: WAU Transmitter (Nadajnik) i WAU Receiver (odbiornik). Po montażu, oba urzÄ
dzenia zostaÅy umieszczone w obudowach.
Oprogramowanie dla mikrokontrolerĆ³w PIC32 zostaÅo stworzone w jÄzyku programowania C. Przetworniki a/c oraz c/a sÄ
kontrolowane przez mikrokontroler i poprawnie realizujÄ
swoje funkcje.
W chwili powstawania tego raportu, problem z obsÅugÄ
transceivera nie zostaÅ rozwiÄ
zany. Z tego powodu, oprogramowanie dla mikrokontrolerĆ³w nie zostaÅo ukoÅczone i urzÄ
dzenie nie posiada zaÅożonej funkcjonalnoÅci
Design and VLSI implementation of a decimation filter for hearing Aid applications
Approximately 10% of the worldās population suffers from some type of hearing loss, yet only small percentage of this statistic use the hearing aid. The stigma associated with wearing a hearing aid, customer dissatisfaction with hearing aid performance, the cost and the battery life. Through the use of digital signal processing the digital hearing aid now offers what the analog hearing aid cannot offer. Currently lot of attention is being given to low power VLSI design. More and more people around the world suffer from hearing losses. The increasing average age and the growing population are the main reasons for this. The decimation filter used for hearing aid applications is designed and implemented both in MATLAB and VHDL. The decimation filter is designed using the distributed arithmetic multiplier in VHDL. Each digital filter structure is simulated using Matlab and its complete architecture is captured using Simulink. The resulting architecture is hardware efficient and consumes less power compared to conventional decimation filters. Compared to the comb-FIR-FIR architecture, the designed decimation filter architecture using Comb-half band FIR-FIR contributes to a hardware saving and reduces the power dissipation
Survey of error concealment schemes for real-time audio transmission systems
This thesis presents an overview of the main strategies employed for error detection and error concealment in different real-time transmission systems for digital audio. The āAdaptive Differential Pulse-Code Modulation (ADPCM)ā, the āAudio Processing Technology Apt-x100ā, the āExtended Adaptive Multi-Rate Wideband (AMR-WB+)ā, the āAdvanced Audio Coding (AAC)ā, the āMPEG-1 Audio Layer II (MP2)ā, the āMPEG-1 Audio Layer III (MP3)ā and finally the āAdaptive Transform Coder 3 (AC3)ā are considered. As an example of error management, a simulation of the AMR-WB+ codec is included. The simulation allows an evaluation of the mechanisms included in the codec definition and enables also an evaluation of the different bit error sensitivities of the encoded audio payload.IngenierĆa TĆ©cnica en TelemĆ”tic