Home medical equipment becomes increasingly popular as VLSI fabrication technology advances. However, there are two important factors for realizing a miniaturized biochip: low noise [1] and low power. Firstly, physiological signals are very susceptible to interference while the amplitude of the signal is only a few millivolts or less. If the circuit cannot reject noise effectively, it is hard to amplify the signal and obtain the output voltage of the recording system accurately. Secondly, it is not convenient to replace the batteries frequently when using the portable measurement instrument for the patients. This thesis is focused on the measurement of physiological signals, such as electrocardiography (ECG) [2], electroneurogram (ENG) [3] and electromyography (EMG) [4] , and designing an all-in-one recording system to measure the different physiological signals in a chip. For this purpose, a programmable multi-parameter system for recording of the wide range of physiological signals is designed. The system provides two types of input transconductance stages, BiCMOS and CMOS. BiCMOS amplifiers provide high gain , low noise [5] and low offset voltage suitable for the small amplitude of the physiological signal. On the other hand, CMOS amplifiers provide practically infinite input impedance and ultra-low leakage current. The system also provides three selectable amplifier modes: (a) double-differential amplifier, (b) single-differential amplifier in channel 1, (c) single-differential amplifier in channel 2. The double-differential amplifier provides a high common-mode rejection and adjustable gain for each channel to further reduce common-mode interference. The single-differential amplifier (channel 1 or channel 2) in the recording system are also accessible as differential-input and single-ended output channels. Moreover, the system provides an offset compensation structure to prevent the amplifier from exceeding the input range. The offset compensation system can selectively be turned off to reduce the power consumption.

This thesis describes a design of a driver for a specific type of laser VCSEL. Models for simulation in PSpice OrCAD have been developed for this type of laser. The qualities of the designed driver aim to be equal to the integrated drivers that are available and to remove some of their drawbacks. It consists of the following components: input LVPECL receiver/driver, differential amplifier, fixed source of a modulation current, circuit of automatic power control. Regulation of the modulation current is dealt with atypically using an aptly selected input LVPECL receiver/driver which enables to control the voltage amplitude on its output by means of voltage. The thesis also describes different types of coupling between laser and driver. The most appropriate alternative is selected taking into consideration the unconventional design of the driver. The connection of the driver is supplemented by a microcontroller which secures control of output optical power by means of a serial bus RS232.

Low size, low power, and wearable bio-signal recording systems require acquisition front-ends with high common-mode rejection for interference suppression and adjustable gain to provide an optimum signal level to a cascading analog-to-digital stage. This thesis presents the realization of microcontroller operated double-differential (DD) recording setup with automatic gain control (AGC) and automatic balance control, which can adjust the magnitude of recorded bio-potential signal to a target level and reject common-mode interference for full-bandwidth recording without filtering. Microcontroller code realizes the automatic control method of gain and balance adjustment by detecting, computing, and varying parameters to set timing clock pulses, which determine the gain magnitude and balance state. The automatic balance control compensates for imbalance in electrode interface impedance. The double-differential amplifier is implemented using two integrated variable gain amplifiers (ASIC) and one adder. Measured results of the variable gain amplifiers fabricated in 0.35 £gm CMOS technology show an input spot noise of 169 nV/¡ÔHz, a NEF below 10, and a circuit active area of 0.017 mm2 with a power consumption of 1.44 £gW. Measured results of the double-differential amplifier setup confirm interference suppression of 25.7 dB, tunable gain range of 39.6 dB, and 239 nV/¡ÔHz noise assuming ¡Ó10% interface mismatch. Practical measured examples incorporating the chips confirm gain control suitable for bio-potential recording and interference suppression in a balanced DD arrangement for electrocardiogram and electromyogram recording.

In this thesis a single stage detector logarithmic video amplifier is designed with a dynamic range of 40dB in 2-6GHz frequency band. Since the detector logarithmic video amplifier (DLVA) is used to convert the power of the RF signals to video voltages in logarithmic scale, it can be regarded as a logarithmic converter instead of logarithmic amplifier. The design is composed of two main parts: The Schottky diode detector rectifies the incoming RF signal and produces a video voltage and the logarithmic amplifier transforms the scale of the video voltage from linear scale to logarithmic scale in order to observe the RF signals with a wide amplitude range. The approximation of the logarithmic function is obtained by the summation of the output currents of the differential amplifiers operating as logarithmic stages. Offset voltage of the DLVA is minimized in order to obtain maximum sensitivity / this makes the detection of RF signals with low power possible. The study is composed of mainly three parts: First, brief information about logarithmic amplification techniques is given and the circuit architecture is developed for logarithmic amplification and video detection, second these circuits are simulated and finally the design is implemented and tested.

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.

Ces travaux de recherche visent à introduire et à généraliser l'utilisation des systèmes différentiels dans les applications RF et Micro-ondes. En particulier, dans la conception de dispositifs pour les fonctions d'amplification à faible bruit. Pour cela, il est indispensable de développer des outils fiables et rigoureux tels que le formalisme des modes mixtes introduit par Bockelman. C'est dans cet esprit que s'inscrit la première phase de l'étude. Le but étant de développer un outil pour l'analyse de la stabilité linéaire des systèmes différentiels à trois et quatre accès. Par ailleurs, les interfaces des circuits numériques ultra-rapides (CNA) sont de topologie différentielle. Ce qui augmente encore l'intérêt de disposer de méthodes rigoureuses pour la conception des systèmes différentiels. Dans la deuxième phase de l'étude la problématique de l'intégration système des CNAs dans les nouvelles générations des chaines de transmission RF des satellites de télécommunications est traitée. La conception d'un balun actif large bande capable d'assurer la conversion de la sortie analogique différentielle du CNA en sortie simple accès (Single-ended) référencée par rapport à la masse est détaillée. Afin de répondre aux contraintes d'intégration, une technologie BiCMOS SiGe 0.25 μm est utilisée pour son implémentation. Les performances obtenues par la mesure de la puce Silicium réalisée respectent les spécifications techniques initiales de l'application. Ce qui permet de valider la méthodologie de conception utilisée. L'objectif final est d'être capable d'intégrer sur un même substrat monolithique le CNA et le balun actif large bande de conversion de modes. / This research work aims to develop analytical tools for the analysis and design of differential systems. While the use of differential circuits in RF reception/transmission chains is increasingly growing, there is no accurate method to study their stability. First the common tools to study RF differential components are introduced. Then, the development of a CAD tool that can be rigorously used to investigate the extrinsic stability of linear differential systems is presented. Finally this tool is applied to study the stability of in a real case. The design addresses a three port component that aims to convert the differential output of digital to analog converter into a single-ended access for a spatial application purpose. This broadband active balun is designed using BiCMOS technology. Measurements are performed and the results are in good agreement with the simulation. All the initial specications are achieved, which validate the approach developed in this study.

The aim of this thesis is design stereo digital to analog convertor for school laboratory usage. Scope of the thesis covers the design of all the functional units: input signal circuit, S/PDIF receiver, D/A converter, high quality analog output stage with active low pass filter. Thesis also cover design of all control and indicating parts containing microcontroller with control parts, alphanumeric OLED display and setting indicators.

This master‘s thesis deals with design and realisation of a control module for automated measurements of the modern contactless inductive position sensors by a mechanical rotational system consisting of a DC motor and an incremental quadrature encoder. The thesis presents methods of driving DC motor and recording of measured data by a microcontroller. The thesis presents a communication protocol between the control module and personal computer via USB interface. A part of this thesis is also to develop a control software and firmware, including the measurement and evaluation of properties of the control module.

The growth in the number of wireless devices and applications underscores the need for characterizing and mitigating interference induced problems such as distortion and blocking. A typical interference scenario involves the detection of a small amplitude signal of interest (SOI) in the presence of a large amplitude interfering signal; it is desirable to attenuate the interfering signal while preserving the integrity of SOI and an appropriate dynamic range. If the frequency of the interfering signal varies or is unknown, an adaptive notch function must be applied in order to maintain adequate attenuation. This work explores the performance space of a phase cancellation technique used in implementing the desired notch function for communication systems in the 1-3 GHz frequency range. A system level model constructed with MATLAB and related simulation results assist in building the theoretical foundation for setting performance bounds on the implemented solution and deriving hardware specifications for the RF notch subsystem devices. Simulations and measurements are presented for a Low Noise Amplifer (LNA), voltage variable attenuators, bandpass filters and phase shifters. Ultimately, full system tests provide a measure of merit for this work as well as invaluable lessons learned. The emphasis of this project is the on-wafer LNA measurements, dependence of IC system performance on mismatches and overall system performance tests. Where possible, predictions are plotted alongside measured data. The reasonable match between the two validates system and component models and more than compensates for the painstaking modeling efforts. Most importantly, using the signal to interferer ratio (SIR) as a figure of merit, experimental results demonstrate up to 58 dB of SIR improvement. This number represents a remarkable advancement in interference rejection at RF or microwave frequencies.

This diploma thesis deals with the method which are useful for analysis of reliability in specific circuit applications. It also deals with fault analysis in frequency, time and DC domain. Methods for these domains are described in other chapter of this thesis. Finally methods for diagnostics analog circuit are evaluated based on simulation and practical testing of selected methods.