Systematic Design of Pseudo-Differential Frequency Filter

In the paper, the theory of systematic design frequency filters is described. The result is a fourth-order pseudo-differential frequency filter operating in the voltagemode and implemented as a cascade connection of two basic second-order blocks. The filter is able to realize the low-pass filtering functions. The basic block employs three active elements and four passive elements. The filter is characterized by a minimum number of passive elements and high output impedance. Filter analysis examines the magnitude, phase, common-mode rejection ratio signal, and behavior of filters while reducing the recommended voltage. The proper functionality of the filter is verified by simulations and experimental measurements for two different interconnections

CFOA-Based Fractional Order PIλDδ Controller

Conventional Current Feedback Operational Amplifier (CFOA) is not current controllable or not electronically controllable. It is thus of interest to add a current mirror into the CFOA in order to make it current controllable. This modification can be achieved by using Diamond Transistor (DT) instead of going through complicated IC fabrication process. This work applies the modified CFOA in fractional order proportional integral derivative (PIλDδ) controller. Both simulation and experimental results confirm that the modified CFOA is electronically controllable

Utilizing Unconventional CMOS Techniques for Low Voltage Low Power Analog Circuits Design for Biomedical Applications

Tato disertační práce se zabývá navržením nízkonapěťových, nízkopříkonových analogových obvodů, které používají nekonvenční techniky CMOS. Lékařská zařízení na bateriové napájení, jako systémy pro dlouhodobý fyziologický monitoring, přenosné systémy, implantovatelné systémy a systémy vhodné na nošení, musí být male a lehké. Kromě toho je nutné, aby byly tyto systémy vybaveny baterií s dlouhou životností. Z tohoto důvodu převládají v biomedicínských aplikacích tohoto typu nízkopříkonové integrované obvody. Nekonvenční techniky jako např. využití transistorů s řízeným substrátem (Bulk-Driven “BD”), s plovoucím hradlem (Floating-Gate “FG”), s kvazi plovoucím hradlem (Quasi-Floating-Gate “QFG”), s řízeným substrátem s plovoucím hradlem (Bulk-Driven Floating-Gate “BD-FG”) a s řízeným substrátem s kvazi plovoucím hradlem (Bulk-Driven Quasi-Floating-Gate “BD-QFG”), se v nedávné době ukázaly jako efektivní prostředek ke zjednodušení obvodového zapojení a ke snížení velikosti napájecího napětí směrem k prahovému napětí u tranzistorů MOS (MOST). V práci jsou podrobně představeny nejdůležitější charakteristiky nekonvenčních technik CMOS. Tyto techniky byly použity pro vytvoření nízko napěťových a nízko výkonových CMOS struktur u některých aktivních prvků, např. Operational Transconductance Amplifier (OTA) založené na BD, FG, QFG, a BD-QFG techniky; Tunable Transconductor založený na BD MOST; Current Conveyor Transconductance Amplifier (CCTA) založený na BD-QFG MOST; Z Copy-Current Controlled-Current Differencing Buffered Amplifier (ZC-CC-CDBA) založený na BD MOST; Winner Take All (WTA) and Loser Take All (LTA) založený na BD MOST; Fully Balanced Four-Terminal Floating Nullor (FBFTFN) založený na BD-QFG technice. Za účelem ověření funkčnosti výše zmíněných struktur, byly tyto struktury použity v několika aplikacích. Výkon navržených aktivních prvků a příkladech aplikací je ověřován prostřednictvím simulačních programů PSpice či Cadence za použití technologie 0.18 m CMOS.This doctoral thesis deals with designing ultra-low-voltage (LV) low-power (LP) analog circuits utilizing the unconventional CMOS techniques. Battery powered medical devices such as; long term physiological monitoring, portable, implantable, and wearable systems need to be small and lightweight. Besides, long life battery is essential need for these devices. Thus, low-power integrated circuits are always paramount in such biomedical applications. Recently, unconventional CMOS techniques i.e. Bulk-Driven (BD), Floating-Gate (FG), Quasi-Floating-Gate (QFG), Bulk-Driven Floating-Gate (BD-FG) and Bulk-Driven Quasi-Floating-Gate (BD-QFG) MOS transistors (MOSTs) have revealed as effective devices to reduce the circuit complexity and push the voltage supply of the circuit towards threshold voltage of the MOST. In this work, the most important features of the unconventional CMOS techniques are discussed in details. These techniques have been utilized to perform ultra-LV LP CMOS structures of several active elements i.e. Operational Transconductance Amplifier (OTA) based on BD, FG, QFG, and BD-QFG techniques; Tunable Transconductor based on BD MOST; Current Conveyor Transconductance Amplifier (CCTA) based on BD-QFG MOST; Z Copy-Current Controlled-Current Differencing Buffered Amplifier (ZC-CC-CDBA) based on BD MOST; Winner Take All (WTA) and Loser Take All (LTA) based on BD MOST; Fully Balanced Four-Terminal Floating Nullor (FBFTFN) based on BD-QFG technique. Moreover, to verify the workability of the proposed structures, they were employed in several applications. The performance of the proposed active elements and their applications were investigated through PSpice or Cadence simulation program using 0.18 m CMOS technology.

Electronically Tunable Fully-Differential Fractional-Order Low-Pass Filter

The paper presents proposal of a fully- differential (1 + )-order low-pass filter. The order of the filter and its cut-off frequency can be controlled electronically. The filter is proposed using operational transconductance amplifiers (OTAs), adjustable current amplifiers (ACAs) and fully-differential current follower (FD-CF). The circuit structure is based on well-known Inverse Follow-the-Leader Feedback (IFLF) topology. Design correctness of the proposed filter is supported by PSpice simulations with transistor-level simulation models. The ability of the electronic control of the order has been tested for five individual values of parameter . Furthermore, the ability of the electronic control of the cut-off frequency of the filter has been also tested for five different values. Additionally, the simulation results of the proposed fully-differential (F-D) filter are compared with the results of the single-ended (S-E) equivalent of the presented filter

Reconnection–less Reconfigurable Fractional–Order Current–Mode Integrator Design with Simple Control

A design of a fractional-order (FO) integrator is introduced for operation of resulting solution in the current mode (CM). The solution of the integrator is based on the utilization of RC structures, but in comparison to other RC structure based FO designs, the proposed integrator offers the electronic control of the order. Moreover, the control of the proposed integrator does not require multiple specific and accurate values of the control voltages/currents in comparison to the topologies based on the approximation of the FO Laplacian operator. The electronic control of a gain level (gain adjustment) of the proposed integrator is available. The paper offers the results of Cadence IC6 (spectre) simulations and more importantly experimental measurements to support the presented design. The proposed integrator can be used to build various FO circuits as demonstrated by the utilization of the integrator into a structure of a frequency filter in order to provide FO characteristics

Optimized fractional low and highpass filters of (1 + α) order on FPAA

This work proposes an optimum design and implementation of fractional-order Butterworth filter of order (1 + α), with the help of analog reconfigurable field-programmable analog array (FPAA). The designed filter coefficients are obtained after dual constraint optimization to balance the tradeoffs between magnitude error and stability margin together. The resulting filter ensures better robustness with less sensitivity to parameter variation and minimum least square error (LSE) in magnitude responses, passband and stopband errors as well as a better –3dB normalized frequency approximation at 1 rad/s and a stability margin. Finally, experimental results have shown both lowpass and highpass fractional step values. The FPAA-configured outputs represent the possibility to implement the real-time fractional filter behavior with close approximation to the theoretical design

Proposal of the fractal order filtering structures

Tato práce se zabývá filtry fraktálního řádu (1+). Navržené filtry pracují v proudovém módu. Odvození těchto filtrů je dosaženo použitím aproximace třetího řádu odpovídající přenosové funkce fraktálního řádu. Jsou zde také popsány aktivní prvky jako univerzální proudový konvejor, proudový sledovač, operační transkonduktanční zesilovač a řiditelný proudový zesilovač. Na konci této práce jsou navržena nová obvodová řešení filtrů fraktálního řádu, která jsou poté realizována a podrobena experimentálnímu měření.This thesis deals with the fractional (1+)-order filters. The proposed filters operate in the current-mode. The derivation of the filters has been achieved using a third-order aproximation of the coresponding fractional-order transfer functions. It also describes active elements such as universal current conveyor, current follower and operational transconductance amplifier. In the end of this thesis some new circuit solutions of the fractional-order filter are proposed. Then the proposed filters are realized and experimentally measured.

Fully-Differential Frequency Filters with Modern Active Elements

Tato disertační práce se zaměřuje na výzkum v oblasti frekvenčních filtrů. Hlavním cílem je navrhnout a analyzovat plně diferenční kmitočtové filtry pracující v proudovém módu a využívající moderní aktivní prvky. Prezentované filtry jsou navrženy za použití proudových sledovačů, operačních transkonduktančních zesilovačů, plně diferenčních proudových zesilovačů a transrezistančních zesilovačů. Návrh se zaměřuje na možnost řídit některý z typických parametrů filtru pomocí řiditelných aktivních prvků, které jsou vhodně umístněny do obvodové struktury. Jednotlivé prezentované filtry jsou navrženy v nediferenční a diferenční verzi. Velký důraz je věnován srovnání plně diferenčních struktur s jejich odpovídajícími nediferenčními formami. Funkčnost jednotlivých návrhů je ověřena simulacemi a v některých případech i experimentálním měřením.This doctoral thesis focuses on research in the field of frequency filters. The main goal is to propose and analyze fully-differential current-mode frequency filters employing modern active elements. Presented filters are proposed using current followers, operational transconductance amplifiers, digitally adjustable current amplifiers and transresistance amplifiers. The proposal is focusing on ability to control some of the typical filter parameter or parameters using controllable active elements suitably placed in the circuit structure. Individual presented filters are proposed in their single-ended and fully-differential forms. Great emphasis is paid to a comparison of the fully-differential structures and their corresponding single-ended forms. The functionality of each proposal is verified by simulations and in some cases also by experimental measurements.