Minimum Configuration Insensitive Multifunctional Current-Mode Biquad Using Current Conveyors and All-Grounded Passive Components

This paper proposes a new current conveyorbased high-output impedance single-input three-output current mode filter with minimum configuration. It contains two dual output second generation current conveyors, one third generation dual output current conveyor, and four grounded resistors and capacitors. The circuit simultaneously provides low-pass, band-pass, and high-pass filtering outputs, without any passive component matching conditions and restrictions on input signals. Additionally, the proposed circuit offers following advantages: Minimum active and passive element count, high output and low input impedances, suitable for cascading identical currentmode sections, all passive elements are grounded (no virtual grounding), low natural frequency and Q-factor sensitivities. The influences of non-ideal current conveyors on the proposed circuit are researched in the last

Unconventional Circuit Elements for Ladder Filter Design

Kmitočtové filtry jsou lineární elektrické obvody, které jsou využívány v různých oblastech elektroniky. Současně tvoří základní stavební bloky pro analogové zpracování signálů. V poslední dekádě bylo zavedeno množství aktivních stavebních bloků pro analogové zpracování signálů. Stále však existuje potřeba vývoje nových aktivních součástek, které by poskytovaly nové možnosti a lepší parametry. V práci jsou diskutovány různé aspekty obvodů pracujících v napěťovém, proudovém a smíšném módu. Práce reaguje na dnešní potřebu nízkovýkonových a nízkonapěťových aplikací pro přenosné přístroje a mobilní komunikační systémy a na problémy jejich návrhu. Potřeba těchto výkonných nízkonapěťových zařízení je výzvou návrhářů k hledání nových obvodových topologií a nových nízkonapěťových technik. V práci je popsána řada aktivních prvků, jako například operační transkonduktanční zesilovač (OTA), proudový konvejor II. generace (CCII) a CDTA (Current Differencing Transconductance Amplifier). Dále jsou navrženy nové prvky, jako jsou VDTA (Voltage Differencing Transconductance Amplifier) a VDVTA (Voltage Differencing Voltage Transconductance Amplifier). Všechny tyto prvky byly rovněž implementovány pomocí "bulk-driven" techniky CMOS s cílem realizace nízkonapěťových aplikací. Tato práce je rovněž zaměřena na náhrady klasických induktorů syntetickými induktory v pasivních LC příčkových filtrech. Tyto náhrady pak mohou vést k syntéze aktivních filtrů se zajímavými vlastnostmi.Frequency filters are linear electric circuits that are used in wide area of electronics. They are also the basic building blocks in analogue signal processing. In the last decade, a huge number of active building blocks for analogue signal processing was introduced. However, there is still the need to develop new active elements that offer new possibilities and better parameters. The current-, voltage-, or mixed-mode analog circuits and their various aspects are discussed in the thesis. This work reflects the trend of low-power (LP) low-voltage (LV) circuits for portable electronic and mobile communication systems and the problems of their design. The need for high-performance LV circuits encourages the analog designers to look for new circuit architectures and new LV techniques. This thesis presents various active elements such as Operational Transconductance Amplifier (OTA), Current Conveyor of Second Generation (CCII), and Current Differencing Transconductance Amplifier (CDTA), and introduces novel ones, such as Voltage Differencing Transconductance Amplifier (VDTA) and Voltage Differencing Voltage Transconductance Amplifier (VDVTA). All the above active elements were also designed in CMOS bulk-driven technology for LP LV applications. This thesis is also focused on replacement of conventional inductors by synthetic ones in passive LC ladder filters. These replacements can lead to the synthesis of active filters with interesting parameters.

Power-efficient current-mode analog circuits for highly integrated ultra low power wireless transceivers

In this thesis, current-mode low-voltage and low-power techniques have been applied to implement novel analog circuits for zero-IF receiver backend design, focusing on amplification, filtering and detection stages. The structure of the thesis follows a bottom-up scheme: basic techniques at device level for low voltage low power operation are proposed in the first place, followed by novel circuit topologies at cell level, and finally the achievement of new designs at system level. At device level the main contribution of this work is the employment of Floating-Gate (FG) and Quasi-Floating-Gate (QFG) transistors in order to reduce the power consumption. New current-mode basic topologies are proposed at cell level: current mirrors and current conveyors. Different topologies for low-power or high performance operation are shown, being these circuits the base for the system level designs. At system level, novel current-mode amplification, filtering and detection stages using the former mentioned basic cells are proposed. The presented current-mode filter makes use of companding techniques to achieve high dynamic range and very low power consumption with for a very wide tuning range. The amplification stage avoids gain bandwidth product achieving a constant bandwidth for different gain configurations using a non-linear active feedback network, which also makes possible to tune the bandwidth. Finally, the proposed current zero-crossing detector represents a very power efficient mixed signal detector for phase modulations. All these designs contribute to the design of very low power compact Zero-IF wireless receivers. The proposed circuits have been fabricated using a 0.5μm double-poly n-well CMOS technology, and the corresponding measurement results are provided and analyzed to validate their operation. On top of that, theoretical analysis has been done to fully explore the potential of the resulting circuits and systems in the scenario of low-power low-voltage applications.Programa Oficial de Doctorado en Tecnologías de las Comunicaciones (RD 1393/2007)Komunikazioen Teknologietako Doktoretza Programa Ofiziala (ED 1393/2007