Voltage-Mode Multifunction Biquadratic Filters Using New Ultra-Low-Power Differential Difference Current Conveyors

This paper presents two low-power voltage-mode multifunction biquadratic filters using differential difference current conveyors. Each proposed circuit employs three differential difference current conveyors, two grounded capacitors and two grounded resistors. The low-voltage ultra-low-power differential difference current conveyor is used to provide low-power consumption of the proposed filters. By appropriately connecting the input and output terminals, the proposed filters can provide low-pass, band-pass, high-pass, band-stop and all-pass voltage responses at high-input terminals, which is a desirable feature for voltage-mode operations. The natural frequency and the quality factor can be orthogonally set by adjusting the circuit components. For realizing all the filter responses, no inverting-type input signal requirements as well as no component-matching conditional requirements are imposed. The incremental parameter sensitivities are also low. The characteristics of the proposed circuits are simulated by using PSPICE simulators to confirm the presented theory

Electronically Tunable Resistorless Mixed Mode Biquad Filters

This paper presents a new realization of elec¬tronically tunable mixed mode (including transadmittance- and voltage-modes) biquad filter with single input, three outputs or three inputs, single output using voltage differ-encing transconductance amplifier (VDTA), a recently introduced active element. It can simultaneously realize standard filtering signals: low-pass, band-pass and high-pass or by selecting input terminals, it can realize all five different filtering signals: low-pass, band-pass, high-pass, band-stop and all-pass. The proposed filter circuit offers the following attractive feature: no requirement of invert-ing type input signal which is require no addition circuit, critical component matching conditions are not required in the design, the circuit parameters ω0 and Q can be set orthogonally or independently through adjusting the bias currents of the VDTAs, the proposed circuit employs two active and minimum numbers of passive components. Fur-thermore, this filter was investigated from the point of view of limited frequency range, stability conditions, effects of parasitic elements and effects of non-ideal and sensitivity. Thus, taking these effects and conditions into considera¬tion, working conditions and boundaries of this filter are determined. We also performed Monte Carlo, THD and noise analyses. Simulation results are given to confirm theoretical analyses

Complex Filters as as a Cascade of of Buffered Gingell Structures: Design from from Band-Stop Constraints

This thesis presents an active Complex Filter implementation that that creates a transfer function with with a single real pole and a complex zero. The two-input/two-output network developed in in this thesis responds differently based upon upon the relative phase difference of of the two inputs. If a negative ninety-degree phase difference occurs between the two inputs, the filter will exhibits a bandstop response. While a positive ninety-degree phase difference exhibits a bandpass response. This topology is relatesd to to Gingell’s RC-CR polyphase topology but because of of the use of of op-amps, can be cascadedd without without suffering loading effects. This thesis will focusfocuses primarily on on the bandstop response characteristics of of the filter. In a several stage cascade, each stage contributes a notch to broaden the attenuation bandWhen several sections are cascaded, multiple notches will be created from each stage that forms a broader attenuation band. Closed form design equations were were derived to to give expressions for for the “attenuation floor”. These equations can be used by a designer to predict the attenuation provided by by a cascaded system. The closed form expressions derived in in this thesis are used to implement an example five-stage topology that that operates from from 147 Hz to to 3.34 KHz. The thesis also investigates the robustness of of multi-stage cascades to to component variations. Monte Carlo analysis is used to determines the effects of of cascading the filter in in different orders, component tolerances, and a comparison to to an idealized polyphase RC-CR topology

Current-Processing Current-Controlled Universal Biquad Filter

This paper presents a current-processing current-controlled universal biquad filter. The proposed filter employs only two current controlled current conveyor transconductance amplifiers (CCCCTAs) and two grounded capacitors. The proposed configuration can be used either as a single input three outputs (SITO) or as three inputs single output (TISO) filter. The circuit realizes all five different standard filter functions i.e. low-pass (LP), band-pass (BP), high-pass (HP), band-reject (BR) and all-pass (AP). The circuit enjoys electronic control of quality factor through the single bias current without disturbing pole frequency. Effects of non-idealities are also discussed. The circuit exhibits low active and passive sensitivity figures. The validity of proposed filter is verified through computer simulations using PSPICE

A unique modulation system for two channel data transmission

A simple low cost system is reported for the telemetry of information from meteorological rocket payloads including parachute borne systems. It uses S- or L-band microwave links with low cost oscillator type transmitters. An extension of this system to transmit two channels of data simultaneously by standard time and frequency multiplexing techniques as a sampled pulse is described. One channel is represented by the pulse repetition rate while the other channel is represented by the instantaneous duty cycle of the pulse train

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.

A portable phonatory feedback device for patients with speech disorders

Vocal intensity-related speech disorders such as dysarthria and vocal nodules can limit quality of life and reduce the patient’s ability to interact with family, socialize, or pursue employment. Behavioral speech therapies exist to address these issues but have limited effectiveness because they are expensive and clinic-based. The ability to monitor vocal intensity outside of the clinical setting will greatly aid in the treatment of these speech disorders, enabling patients to make quicker progress by reinforcing techniques learned in the clinic. The Voice Volume Monitor (VVM) is a portable and cost-effective therapeutic aid designed for this purpose, providing real-time feedback regarding speech volume to the user. Initial testing of a prototype with patients at the Our Lady of the Lake Voice Center has shown positive results

Active Noise Control Using Modally Tuned Phase-Compensated Filters

An active noise control device or an active noise absorber (ANA) that is based on either resonant 2nd - order or 4th - order Butterworth filters is developed and demonstrated. This control method is similar to structural positive position feedback (PPF) control, with two exceptions: 1) acoustic transducers (microphone and speaker) can not be truly colocated, and 2) the acoustic actuator (loudspeaker) has significant dynamics that can affect performance and stability. Acoustic modal control approaches are typically not sought, however, there are a number of applications where controlling a few room modes is adequate. A model of a duct with speakers at each end is developed and used to demonstrate the control method, including the impact of the speaker dynamics. An all-pass filter is used to provide phase compensation and improve controller performance. Two companion experimental studies validated the simulation results. A single mode case using a resonant band-pass filter demonstrated nearly 10 dB of control in the first duct, while a multimodal case using two 4th - order Butterworth band-pass filters show both 10 dB of reduction in the fundamental mode and nearly 8.0 dB in the second

Wearable impedance plethysmography and electrocardiography sensor

Wearable technology has become increasingly popular in the last few years. This project describes the design and implementation of a wearable impedance plethysmography and electrocardiography sensor. This sensor is developed to be compact and lightweight while having a very extended battery life. This way, it can be easily integrated into other wearable devices or into clothing or shoes. The acquired IPG and ECG data will be transmitted in real-time to a receiving host for further storage and processing by using the Bluetooth Low Energy protocol. By using a so widespread low energy wireless protocol, the data can be received into any compatible device, such as smartphones, laptops or even specialized systems. An android application showing a real-time graphic of the measured signals is also developed for demonstration purposes. To meet the low power consumption requirements of the analog front-end circuitry, multiple techniques were used, such as using low power versions of components such as operational amplifiers and even taking advantage of their limitations to improve circuit performance characteristics. Other techniques such as sensing the correct placement of electrodes or disabling parts of the circuitry when not needed or the signal is not available were also used. A current consumption for the analog frontend in the order of only 100 µA to 200 µA at 3V was achieved while continuously providing both IPG and ECG data. For the digital circuitry, consisting mainly of the nRF51822 System on Chip from Nordic Semiconductor and some peripherals, multiple techniques of power consumption minimization were also used. A current consumption of around 200 µA to 300 µA was achieved, again at 3V, during continuous data processing and transmission. A prototype was implemented on a PCB. Unfortunately, full functionality was not achieved mainly due to some hardware failures and time constraints, however, as multiple innovative solutions were implemented, this work will provide useful information to improve other research projects in this area.Objectius de Desenvolupament Sostenible::3 - Salut i Benesta