76 research outputs found
Novel active function blocks and their applications in frequency filters and quadrature oscillators
KmitoÄtovĂ© filtry a sinusoidnĂ oscilĂĄtory jsou lineĂĄrnĂ elektronickĂ© obvody, kterĂ© jsou pouĆŸĂvĂĄny v ĆĄirokĂ© oblasti elektroniky a jsou zĂĄkladnĂmi stavebnĂmi bloky v analogovĂ©m zpracovĂĄnĂ signĂĄlu. V poslednĂ dekĂĄdÄ pro tento ĂșÄel bylo prezentovĂĄno velkĂ© mnoĆŸstvĂ stavebnĂch funkÄnĂch blokĆŻ. V letech 2000 a 2006 na Ăstavu telekomunikacĂ, VUT v BrnÄ byly definovĂĄny univerzĂĄlnĂ proudovĂœ konvejor (UCC) a univerzĂĄlnĂ napÄt'ovĂœ konvejor (UVC) a vyrobeny ve spoluprĂĄci s firmou AMI Semiconductor Czech, Ltd. OvĆĄem, stĂĄle existuje poĆŸadavek na vĂœvoj novĂœch aktivnĂch prvkĆŻ, kterĂ© nabĂzejĂ novĂ© vĂœhody. HlavnĂ pĆĂnos prĂĄce proto spoÄĂvĂĄ v definici dalĆĄĂch pĆŻvodnĂch aktivnĂch stavebnĂch blokĆŻ 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-). PomocĂ navrĆŸenĂœch aktivnĂch stavebnĂch blokĆŻ byly prezentovĂĄny pĆŻvodnĂ zapojenĂ fĂĄzovacĂch ÄlĂĄnkĆŻ prvnĂho ĆĂĄdu, univerzĂĄlnĂ filtry druhĂ©ho ĆĂĄdu, ekvivalenty obvodu typu KHN, inverznĂ filtry, aktivnĂ simulĂĄtory uzemnÄnĂ©ho induktoru a kvadraturnĂ sinusoidnĂ oscilĂĄtory pracujĂcĂ v proudovĂ©m, napÄt'ovĂ©m a smĂĆĄenĂ©m mĂłdu. ChovĂĄnĂ navrĆŸenĂœch obvodĆŻ byla ovÄĆena simulacĂ v prostĆedĂ SPICE a ve vybranĂœch pĆĂpadech experimentĂĄlnĂm mÄĆenĂm.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 circuitâs 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 authorâs 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
Unconventional Circuit Elements for Ladder Filter Design
KmitoÄtovĂ© filtry jsou lineĂĄrnĂ elektrickĂ© obvody, kterĂ© jsou vyuĆŸĂvĂĄny v rĆŻznĂœch oblastech elektroniky. SouÄasnÄ tvoĆĂ zĂĄkladnĂ stavebnĂ bloky pro analogovĂ© zpracovĂĄnĂ signĂĄlĆŻ. V poslednĂ dekĂĄdÄ bylo zavedeno mnoĆŸstvĂ aktivnĂch stavebnĂch blokĆŻ pro analogovĂ© zpracovĂĄnĂ signĂĄlĆŻ. StĂĄle vĆĄak existuje potĆeba vĂœvoje novĂœch aktivnĂch souÄĂĄstek, kterĂ© by poskytovaly novĂ© moĆŸnosti a lepĆĄĂ parametry. V prĂĄci jsou diskutovĂĄny rĆŻznĂ© aspekty obvodĆŻ pracujĂcĂch v napÄĆ„ovĂ©m, proudovĂ©m a smĂĆĄnĂ©m mĂłdu. PrĂĄce reaguje na dneĆĄnĂ potĆebu nĂzkovĂœkonovĂœch a nĂzkonapÄĆ„ovĂœch aplikacĂ pro pĆenosnĂ© pĆĂstroje a mobilnĂ komunikaÄnĂ systĂ©my a na problĂ©my jejich nĂĄvrhu. PotĆeba tÄchto vĂœkonnĂœch nĂzkonapÄĆ„ovĂœch zaĆĂzenĂ je vĂœzvou nĂĄvrhĂĄĆĆŻ k hledĂĄnĂ novĂœch obvodovĂœch topologiĂ a novĂœch nĂzkonapÄĆ„ovĂœch technik. V prĂĄci je popsĂĄna Ćada aktivnĂch prvkĆŻ, jako napĆĂklad operaÄnĂ transkonduktanÄnĂ zesilovaÄ (OTA), proudovĂœ konvejor II. generace (CCII) a CDTA (Current Differencing Transconductance Amplifier). DĂĄle jsou navrĆŸeny novĂ© prvky, jako jsou VDTA (Voltage Differencing Transconductance Amplifier) a VDVTA (Voltage Differencing Voltage Transconductance Amplifier). VĆĄechny tyto prvky byly rovnÄĆŸ implementovĂĄny pomocĂ "bulk-driven" techniky CMOS s cĂlem realizace nĂzkonapÄĆ„ovĂœch aplikacĂ. Tato prĂĄce je rovnÄĆŸ zamÄĆena na nĂĄhrady klasickĂœch induktorĆŻ syntetickĂœmi induktory v pasivnĂch LC pĆĂÄkovĂœch filtrech. Tyto nĂĄhrady pak mohou vĂ©st k syntĂ©ze aktivnĂch filtrĆŻ se zajĂmavĂœmi 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.
Circuits for Analog Signal Processing Employing Unconventional Active Elements
DisertaÄnĂ prĂĄce se zabĂœvĂĄ zavĂĄdÄnĂm novĂœch struktur modernĂch aktivnĂch prvkĆŻ pracujĂcĂch v napÄĆ„ovĂ©m, proudovĂ©m a smĂĆĄenĂ©m reĆŸimu. FunkÄnost a chovĂĄnĂ tÄchto prvkĆŻ byly ovÄĆeny prostĆednictvĂm SPICE simulacĂ. V tĂ©to prĂĄci je zahrnuta Ćada simulacĂ, kterĂ© dokazujĂ pĆesnost a dobrĂ© vlastnosti tÄchto prvkĆŻ, pĆiÄemĆŸ velkĂœ dĆŻraz byl kladen na to, aby tyto prvky byly schopny pracovat pĆi nĂzkĂ©m napĂĄjecĂm napÄtĂ, jelikoĆŸ poptĂĄvka po pĆenosnĂœch elektronickĂœch zaĆĂzenĂch a implantabilnĂch zdravotnickĂœch pĆĂstrojĂch stĂĄle roste. Tyto pĆĂstroje jsou napĂĄjeny bateriemi a k tomu, aby byla prodlouĆŸena jejich ĆŸivotnost, trend navrhovĂĄnĂ analogovĂœch obvodĆŻ smÄĆuje k stĂĄle vÄtĆĄĂmu sniĆŸovĂĄnĂ spotĆeby a napĂĄjecĂho napÄtĂ. HlavnĂm pĆĂnosem tĂ©to prĂĄce je nĂĄvrh novĂœch CMOS struktur: CCII (Current Conveyor Second Generation) na zĂĄkladÄ BD (Bulk Driven), FG (Floating Gate) a QFG (Quasi Floating Gate); DVCC (Differential Voltage Current Conveyor) na zĂĄkladÄ FG, transkonduktor na zĂĄkladÄ novĂ© techniky BD_QFG (Bulk Driven_Quasi Floating Gate), CCCDBA (Current Controlled Current Differencing Buffered Amplifier) na zĂĄkladÄ GD (Gate Driven), VDBA (Voltage Differencing Buffered Amplifier) na zĂĄkladÄ GD a DBeTA (Differential_Input Buffered and External Transconductance Amplifier) na zĂĄkladÄ BD. DĂĄle je uvedeno nÄkolik zajĂmavĂœch aplikacĂ uĆŸĂvajĂcĂch vĂœĆĄe jmenovanĂ© prvky. ZĂskanĂ© vĂœsledky simulacĂ odpovĂdajĂ teoretickĂœm pĆedpokladĆŻm.The dissertation thesis deals with implementing new structures of modern active elements working in voltage_, current_, and mixed mode. The functionality and behavior of these elements have been verified by SPICE simulation. Sufficient numbers of simulated plots are included in this thesis to illustrate the precise and strong behavior of those elements. However, a big attention to implement active elements by utilizing LV LP (Low Voltage Low Power) techniques is given in this thesis. This attention came from the fact that growing demand of portable electronic equipments and implantable medical devices are pushing the development towards LV LP integrated circuits because of their influence on batteries lifetime. More specifically, the main contribution of this thesis is to implement new CMOS structures of: CCII (Current Conveyor Second Generation) based on BD (Bulk Driven), FG (Floating Gate) and QFG (Quasi Floating Gate); DVCC (Differential Voltage Current Conveyor) based on FG; Transconductor based on new technique of BD_QFG (Bulk Driven_Quasi Floating Gate); CCCDBA (Current Controlled Current Differencing Buffered Amplifier) based on conventional GD (Gate Driven); VDBA (Voltage Differencing Buffered Amplifier) based on GD. Moreover, defining new active element i.e. DBeTA (Differential_Input Buffered and External Transconductance Amplifier) based on BD is also one of the main contributions of this thesis. To confirm the workability and attractive properties of the proposed circuits many applications were exhibited. The given results agree well with the theoretical anticipation.
New Current-Mode Bandpass Filters Using Three Single-Output ICCIIs
New current-mode bandpass filters using three single
outputs inverting second generation current conveyors (ICCII) are
introduced. The first circuit uses two ICCII+ and one
ICCIIâ, and realizes
an inverting bandpass response. This circuit has one floating
resistor and no independent gain control. The second circuit
uses three ICCIIâ and
realizes a noninverting bandpass response. The third circuit uses
three ICCII+ and realizes also a noninverting bandpass response.
The second and third circuits employ four grounded resistors and
two grounded capacitors and have independent control on
Q and on the center frequency gain by varying a
single grounded resistor. Spice simulation results using
0.5âum CMOS transistors are included to support the
theoretical analysis
Study of Adjustable Gains for Control of Oscillation Frequency and Oscillation Condition in 3R-2C Oscillator
An idea of adjustable gain in order to obtain controllable features is very useful for design of tuneable oscillators. Several active elements with adjustable properties (current and voltage gain) are discussed in this paper. Three modified oscillator conceptions that are quite simple, directly electronically adjustable, providing independent control of oscillation condition and frequency were designed. Positive and negative aspects of presented method of control are discussed. Expected assumptions of adjustability are verified experimentally on one of the presented solution
Utilizing Unconventional CMOS Techniques for Low Voltage Low Power Analog Circuits Design for Biomedical Applications
Tato disertaÄnĂ prĂĄce se zabĂœvĂĄ navrĆŸenĂm nĂzkonapÄĆ„ovĂœch, nĂzkopĆĂkonovĂœch analogovĂœch obvodĆŻ, kterĂ© pouĆŸĂvajĂ nekonvenÄnĂ techniky CMOS. LĂ©kaĆskĂĄ zaĆĂzenĂ na bateriovĂ© napĂĄjenĂ, jako systĂ©my pro dlouhodobĂœ fyziologickĂœ monitoring, pĆenosnĂ© systĂ©my, implantovatelnĂ© systĂ©my a systĂ©my vhodnĂ© na noĆĄenĂ, musĂ bĂœt male a lehkĂ©. KromÄ toho je nutnĂ©, aby byly tyto systĂ©my vybaveny bateriĂ s dlouhou ĆŸivotnostĂ. Z tohoto dĆŻvodu pĆevlĂĄdajĂ v biomedicĂnskĂœch aplikacĂch tohoto typu nĂzkopĆĂkonovĂ© integrovanĂ© obvody. NekonvenÄnĂ techniky jako napĆ. vyuĆŸitĂ transistorĆŻ s ĆĂzenĂœm substrĂĄtem (Bulk-Driven âBDâ), s plovoucĂm hradlem (Floating-Gate âFGâ), s kvazi plovoucĂm hradlem (Quasi-Floating-Gate âQFGâ), s ĆĂzenĂœm substrĂĄtem s plovoucĂm hradlem (Bulk-Driven Floating-Gate âBD-FGâ) a s ĆĂzenĂœm substrĂĄtem s kvazi plovoucĂm hradlem (Bulk-Driven Quasi-Floating-Gate âBD-QFGâ), se v nedĂĄvnĂ© dobÄ ukĂĄzaly jako efektivnĂ prostĆedek ke zjednoduĆĄenĂ obvodovĂ©ho zapojenĂ a ke snĂĆŸenĂ velikosti napĂĄjecĂho napÄtĂ smÄrem k prahovĂ©mu napÄtĂ u tranzistorĆŻ MOS (MOST). V prĂĄci jsou podrobnÄ pĆedstaveny nejdĆŻleĆŸitÄjĆĄĂ charakteristiky nekonvenÄnĂch technik CMOS. Tyto techniky byly pouĆŸity pro vytvoĆenĂ nĂzko napÄĆ„ovĂœch a nĂzko vĂœkonovĂœch CMOS struktur u nÄkterĂœch aktivnĂch prvkĆŻ, napĆ. Operational Transconductance Amplifier (OTA) zaloĆŸenĂ© na BD, FG, QFG, a BD-QFG techniky; Tunable Transconductor zaloĆŸenĂœ na BD MOST; Current Conveyor Transconductance Amplifier (CCTA) zaloĆŸenĂœ na BD-QFG MOST; Z Copy-Current Controlled-Current Differencing Buffered Amplifier (ZC-CC-CDBA) zaloĆŸenĂœ na BD MOST; Winner Take All (WTA) and Loser Take All (LTA) zaloĆŸenĂœ na BD MOST; Fully Balanced Four-Terminal Floating Nullor (FBFTFN) zaloĆŸenĂœ na BD-QFG technice. Za ĂșÄelem ovÄĆenĂ funkÄnosti vĂœĆĄe zmĂnÄnĂœch struktur, byly tyto struktury pouĆŸity v nÄkolika aplikacĂch. VĂœkon navrĆŸenĂœch aktivnĂch prvkĆŻ a pĆĂkladech aplikacĂ je ovÄĆovĂĄn prostĆednictvĂm simulaÄnĂch programĆŻ PSpice Äi Cadence za pouĆŸitĂ 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.
Low Voltage Low Power Analogue Circuits Design
DisertaÄnĂ prĂĄce je zamÄĆena na vĂœzkum nejbÄĆŸnÄjĆĄĂch metod, kterĂ© se vyuĆŸĂvajĂ pĆi nĂĄvrhu analogovĂœch obvodĆŻ s vyuĆŸitĂ nĂzkonapÄĆ„ovĂœch (LV) a nĂzkopĆĂkonovĂœch (LP) struktur. Tyto LV LP obvody mohou bĂœt vytvoĆeny dĂky vyspÄlĂœm technologiĂm nebo takĂ© vyuĆŸitĂm pokroÄilĂœch technik nĂĄvrhu. DisertaÄnĂ prĂĄce se zabĂœvĂĄ prĂĄvÄ pokroÄilĂœmi technikami nĂĄvrhu, pĆedevĆĄĂm pak nekonvenÄnĂmi. Mezi tyto techniky patĆĂ vyuĆŸitĂ prvkĆŻ s ĆĂzenĂœm substrĂĄtem (bulk-driven - BD), s plovoucĂm hradlem (floating-gate - FG), s kvazi plovoucĂm hradlem (quasi-floating-gate - QFG), s ĆĂzenĂœm substrĂĄtem s plovoucĂm hradlem (bulk-driven floating-gate - BD-FG) a s ĆĂzenĂœm substrĂĄtem s kvazi plovoucĂm hradlem (quasi-floating-gate - BD-QFG). PrĂĄce je takĂ© orientovĂĄna na moĆŸnĂ© zpĆŻsoby implementace znĂĄmĂœch a modernĂch aktivnĂch prvkĆŻ pracujĂcĂch v napÄĆ„ovĂ©m, proudovĂ©m nebo mix-mĂłdu. Mezi tyto prvky lze zaÄlenit zesilovaÄe typu OTA (operational transconductance amplifier), CCII (second generation current conveyor), FB-CCII (fully-differential second generation current conveyor), FB-DDA (fully-balanced differential difference amplifier), VDTA (voltage differencing transconductance amplifier), CC-CDBA (current-controlled current differencing buffered amplifier) a CFOA (current feedback operational amplifier). Za ĂșÄelem potvrzenĂ funkÄnosti a chovĂĄnĂ vĂœĆĄe zmĂnÄnĂœch struktur a prvkĆŻ byly vytvoĆeny pĆĂklady aplikacĂ, kterĂ© simulujĂ usmÄrĆovacĂ a induktanÄnĂ vlastnosti diody, dĂĄle pak filtry dolnĂ propusti, pĂĄsmovĂ© propusti a takĂ© univerzĂĄlnĂ filtry. VĆĄechny aktivnĂ prvky a pĆĂklady aplikacĂ byly ovÄĆeny pomocĂ PSpice simulacĂ s vyuĆŸitĂm parametrĆŻ technologie 0,18 m TSMC CMOS. Pro ilustraci pĆesnĂ©ho a ĂșÄinnĂ©ho chovĂĄnĂ struktur je v disertaÄnĂ prĂĄci zahrnuto velkĂ© mnoĆŸstvĂ simulaÄnĂch vĂœsledkĆŻ.The dissertation thesis is aiming at examining the most common methods adopted by analog circuits' designers in order to achieve low voltage (LV) low power (LP) configurations. The capability of LV LP operation could be achieved either by developed technologies or by design techniques. The thesis is concentrating upon design techniques, especially the nonâconventional ones which are bulkâdriven (BD), floatingâgate (FG), quasiâfloatingâgate (QFG), bulkâdriven floatingâgate (BDâFG) and bulkâdriven quasiâfloatingâgate (BDâQFG) techniques. The thesis also looks at ways of implementing structures of wellâknown and modern active elements operating in voltageâ, currentâ, and mixedâmode such as operational transconductance amplifier (OTA), second generation current conveyor (CCII), fullyâdifferential second generation current conveyor (FBâCCII), fullyâbalanced differential difference amplifier (FBâDDA), voltage differencing transconductance amplifier (VDTA), currentâcontrolled current differencing buffered amplifier (CCâCDBA) and current feedback operational amplifier (CFOA). In order to confirm the functionality and behavior of these configurations and elements, they have been utilized in application examples such as diodeâless rectifier and inductance simulations, as well as lowâpass, bandâpass and universal filters. All active elements and application examples have been verified by PSpice simulator using the 0.18 m TSMC CMOS parameters. Sufficient numbers of simulated plots are included in this thesis to illustrate the precise and strong behavior of structures.
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 (CCIIâ) 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 ÎŒm CMOS-process. These filters use a differential CCIIâ 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 ÎŒm BiCMOS-process, uses again a CCIIâ. This circuit uses a pn-junction as a logarithmic feedback element. With a CCIIâ 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 ÎŒm 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
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