Novel active function blocks and their applications in frequency filters and quadrature oscillators

Kmitočtové filtry a sinusoidní oscilátory jsou lineární elektronické obvody, které jsou používány v široké oblasti elektroniky a jsou základními stavebními bloky v analogovém zpracování signálu. V poslední dekádě pro tento účel bylo prezentováno velké množství stavebních funkčních bloků. V letech 2000 a 2006 na Ústavu telekomunikací, VUT v Brně byly definovány univerzální proudový konvejor (UCC) a univerzální napět'ový konvejor (UVC) a vyrobeny ve spolupráci s firmou AMI Semiconductor Czech, Ltd. Ovšem, stále existuje požadavek na vývoj nových aktivních prvků, které nabízejí nové výhody. Hlavní přínos práce proto spočívá v definici dalších původních aktivních stavebních bloků jako jsou differential-input buffered and transconductance amplifier (DBTA), current follower transconductance amplifier (CFTA), z-copy current-controlled current inverting transconductance amplifier (ZC-CCCITA), generalized current follower differential input transconductance amplifier (GCFDITA), voltage gain-controlled modified current-feedback operational amplifier (VGC-MCFOA), a minus-type current-controlled third-generation voltage conveyor (CC-VCIII-). Pomocí navržených aktivních stavebních bloků byly prezentovány původní zapojení fázovacích článků prvního řádu, univerzální filtry druhého řádu, ekvivalenty obvodu typu KHN, inverzní filtry, aktivní simulátory uzemněného induktoru a kvadraturní sinusoidní oscilátory pracující v proudovém, napět'ovém a smíšeném módu. Chování navržených obvodů byla ověřena simulací v prostředí SPICE a ve vybraných případech experimentálním měřením.Frequency filters and sinusoidal oscillators are linear electric circuits that are used in wide area of electronics and also are the basic building blocks in analogue signal processing. In the last decade, huge number of active building blocks (ABBs) were presented for this purpose. In 2000 and 2006, the universal current conveyor (UCC) and the universal voltage conveyor (UVC), respectively, were designed at the Department of Telecommunication, BUT, Brno, and produced in cooperation with AMI Semiconductor Czech, Ltd. There is still the need to develop new active elements that offer new advantages. The main contribution of this thesis is, therefore, the definition of other novel ABBs such as the differential-input buffered and transconductance amplifier (DBTA), the current follower transconductance amplifier (CFTA), the z-copy current-controlled current inverting transconductance amplifier (ZC-CCCITA), the generalized current follower differential input transconductance amplifier (GCFDITA), the voltage gain-controlled modified current-feedback operational amplifier (VGC-MCFOA), and the minus-type current-controlled third-generation voltage conveyor (CC-VCIII-). Using the proposed ABBs, novel structures of first-order all-pass filters, second-order universal filters, KHN-equivalent circuits, inverse filters, active grounded inductance simulators, and quadrature sinusoidal oscillators working in the current-, voltage-, or mixed-mode are presented. The behavior of the proposed circuits has been verified by SPICE simulations and in selected cases also by experimental measurements.

Design of the fully differential operational floating conveyor and its applications

Analog circuits can be generally classified into two broad categories: The first one includes analog circuits operating in the voltage mode, while the second category includes those operating in the current mode. Voltage mode analog circuit’s bandwidth is highly dependent on the gain via the gain bandwidth product (GBP). To solve this problem, many current mode circuits are developed such as the second generation Current Conveyor (CCII) and the Operational Floating Conveyor (OFC). A novel concept of the Fully Differential Operational Floating Conveyor (FD-OFC) is presented for the first time, to the best of the author’s knowledge. A CMOS design for the proposed FD-OFC is introduced as an 8 (4x4) port general purpose analog building block. The FD-OFC design is implemented using two different realizations. The proposed design has the advantage of low power consumption as it operates under biasing conditions of only 1.2 V while its wide bandwidth reaches 600 MHz. These operating conditions recommend the proposed device to be integrated to a wide range of low power-wide high speed applications. The terminal behavior of the proposed device is mathematically modeled and its operation is simulated using the UMC 130 nm technology kit in Cadence environment. Differential voltage amplifier, current mode instrumentation amplifier (CMIA) and Fully Differential second generation Current Conveyor (FDCCII) are examples of the presented applications based on the proposed FD-OFC

Chemical Current-Conveyor: a new approach in biochemical computation

Biochemical sensors that are low cost, small in size and compatible with integrated circuit technology play an essential part in the drive towards personalised healthcare and the research described in this thesis is concerned with this area of medical instrumentation. A new biochemical measurement system able to sense key properties of biochemical fluids is presented. This new integrated circuit biochemical sensor, called the Chemical Current-Conveyor, uses the ion sensitive field effect transistor as the input sensor combined with the current-conveyor, an analog building-block, to produce a range of measurement systems. The concept of the Chemical Current-Conveyor is presented together with the design and subsequent fabrication of a demonstrator integrated circuit built on conventional 0.35μm CMOS silicon technology. The silicon area of the Chemical Current-Conveyor is (92μm x 172μm) for the N-channel version and (99μm x 165μm) for the P-channel version. Power consumption for the N-channel version is 30μW and 43μW for the P-channel version with a full load of 1MΩ. The maximum sensitivity achieved for pH measurement was 46mV per pH. The potential of the Chemical Current Conveyor as a versatile biochemical integrated circuit, able to produce output information in an appropriate form for direct clinical use has been confirmed by applications including measurement of (i) pH, (ii) buffer index ( ), (iii) urea, (iv) creatinine and (v) urea:creatinine ratio. In all five cases the device has been demonstrated successfully, confirming the validity of the original aim of this research project, namely to produce a versatile and flexible analog circuit for many biochemical measurement applications. Finally, the thesis closes with discussion of another potential application area for the Chemical Current Conveyor and the main contributions can be summarised by the design and development of the first: ISFET based current-conveyor biochemical sensor, called 'Chemical Current Conveyor, CCCII+' has been designed and developed. It is a general purpose biochemical analog building-block for several biochemical measurements. Real-time buffer capacity measurement system, based on the CCCII+, which exploits the imbedded analog computation capability of the CCCII+. Real-time enzyme based CCCII+ namely, Creatinine-CCCII+ and Urea-CCCII+ for real-time monitoring system of renal system. The system can provide outputs of 3 important parameters of the renal system, namely (i) urea concentration, (ii) creatinine concentration, and (ii) urea to creatinine ratio

CMOS current amplifiers : speed versus nonlinearity

This work deals with analogue integrated circuit design using various types of current-mode amplifiers. These circuits are analysed and realised using modern CMOS integration technologies. The dynamic nonlinearities of these circuits are discussed in detail as in the literature only linear nonidealities and static nonlinearities are conventionally considered. For the most important open-loop current-mode amplifier, the second-generation current-conveyor (CCII), a macromodel is derived that, unlike other reported macromodels, can accurately predict the common-mode behaviour in differential applications. Similarly, this model is used to describe the nonidealities of several other current-mode amplifiers because similar circuit structures are common in such amplifiers. With modern low-voltage CMOS-technologies, the current-mode operational amplifier and the high-gain current-conveyor (CCII∞) perform better than open-loop current-amplifiers. Similarly, unlike with conventional voltage-mode operational amplifiers, the large-signal settling behaviour of these two amplifier types does not degrade as CMOS-processes are scaled down. In this work, two 1 MHz 3rd -order low-pass continuous-time filters are realised with a 1.2 μm CMOS-process. These filters use a differential CCII∞ with linearised, dynamically biased output stages resulting in performance superior to most OTA-C filter realisations reported. Similarly, two logarithmic amplifier chips are designed and fabricated. The first circuit, implemented with a 1.2 μm BiCMOS-process, uses again a CCII∞. This circuit uses a pn-junction as a logarithmic feedback element. With a CCII∞ the constant gain-bandwidth product, typical of voltage-mode operational amplifiers, is avoided resulting in a constant 1 MHz bandwidth with a 60 dB signal amplitude range. The second current-mode logarithmic amplifier, based on piece-wise linear approximation of the logarithmic function by a cascade of limiting current amplifier stages, is realised in a standard 1.2 μm CMOS-process. The limiting level in these current amplifiers is less sensitive to process variation than in limiting voltage amplifiers resulting in exceptionally low temperature dependency of the logarithmic output signal. Additionally, along with this logarithmic amplifier a new current peak detectoris developed.reviewe

Real-time control of industrial robots in multiple microcomputers

Imperial Users onl

A high-performance, multi-frequency micro-controlled Electrical Impedance Mammography (EIM) excitation and phantom validation system

The research concentrates on the design, development and calibration of a high performance Electrical Impedance Mammography (EIM) system for early detection of breast cancer at the macro and micro scale (at an early stage applicable for different breast sizes and shapes). The enhancement of the Electrical Impedance Tomography (EIT) system focuses on developing electrical and electronic instrumentations and improving the current source topologies to make them operate at multiple frequencies for the purpose of measuring permittivity and conductivity of different breast tissues. The calibration, assessment systems have employed current calibration in the EIT to evaluate the impedance distribution. This facilitates the acquisition of accurate impedance images to enable images of the internal structure of the breast to be constructed. A constraint on EIT systems is that the current injection system suffers from the effects of stray capacitance having a major impact on the hardware subsystem as the EIT is an ill-posed inverse problem which depends on the noise level in EIT measured data and regularization parameter in the reconstruction algorithm. This research aims are to prevent this problem by using a capacitance cancellation method based on a General Impedance Converter (GIC) implemented by operation of a second generation of current conveyor called OCCII-GIC and calibration methods to facilitate operation in the high frequency range. An EIT system based on a planar 85-electrode channel and using a Microcontroller unit (MCU) for addressing control between 85 electrodes and implementing calibration methods has been constructed. In EIT systems, assessment, validation of the performance and calibration of systematic errors in the electrical field generated inside of the interrogated volume is important. Evaluation of the EIT system will be assessed using a realistic electronic phantom (E-phantom). This enables the evaluation of the different conductivity values of the tissue, which has been created and evaluated based on the RSC circuit model for the different electrical conductivities and electrical impedivities in breast tissue

Mixed-Mode Third-Order Quadrature Oscillator Based on Single MCCFTA

This paper presents a new mixed-mode third-order quadrature oscillator based on new modified current-controlled current follower transconductance amplifier (MCCFTA). The proposed circuit employs one MCCFTA as active element and three grounded capacitors as passive component which is highly suitable for integrated circuit implementation. The condition and frequency of oscillations can be controlled orthogonally and electronically by adjusting the bias currents of the active device. The circuit provides four quadrature current outputs and two quadrature voltage outputs into one single topology, which can be classified as mixed-mode oscillator. In addition, four quadrature current output terminals possess high-impedance level which can be directly connected to next stage without additional buffer circuits. The performance of the proposed structure has been verified through PSPICE simulators using 0.25 µm CMOS process from TSMC and experimental results are also investigated

A Photoplethysmography System Optimised for Pervasive Cardiac Monitoring

Photoplethysmography is a non-invasive sensing technique which infers instantaneous cardiac function from an optical measurement of blood vessels. This thesis presents a photoplethysmography based sensor system that has been developed speci fically for the requirements of a pervasive healthcare monitoring system. Continuous monitoring of patients requires both the size and power consumption of the chosen sensor solution to be minimised to ensure the patients will be willing to use the device. Pervasive sensing also requires that the device be scalable for manufacturing in high volume at a build cost that healthcare providers are willing to accept. System level choice of both electronic circuits and signal processing techniques are based on their sensitivity to cardiac biosignals, robustness against noise inducing artefacts and simplicity of implementation. Numerical analysis is used to justify the implementation of a technique in hardware. Circuit prototyping and experimental data collection is used to validate a technique's application. The entire signal chain operates in the discrete-time domain which allows all of the signal processing to be implemented in firmware on an embedded processor which minimised the number of discrete components while optimising the trade-off between power and bandwidth in the analogue front-end. Synchronisation of the optical illumination and detection modules enables high dynamic range rejection of both AC and DC independent light sources without compromising the biosignal. Signal delineation is used to reduce the required communication bandwidth as it preserves both amplitude and temporal resolution of the non-stationary photoplethysmography signals allowing more complicated analytical techniques to be performed at the other end of communication channel. The complete sensing system is implemented on a single PCB using only commercial-off -the-shelf components and consumes less than 7.5mW of power. The sensor platform is validated by the successful capture of physiological data in a harsh optical sensing environment