All-Pass Filter Based Linear Voltage Controlled Quadrature Oscillator

A linear voltage controlled quadrature oscillator implemented from a first-order electronically tunable all-pass filter (ETAF) is presented. The active element is commercially available current feedback amplifier (AD844) in conjunction with the relatively new Multiplication Mode Current Conveyor (MMCC) device. Electronic tunability is obtained by the control node voltage (V) of the MMCC. Effects of the device nonidealities, namely, the parasitic capacitors and the roll-off poles of the port-transfer ratios of the device, are shown to be negligible, even though the usable high-frequency ranges are constrained by these imperfections. Subsequently the filter is looped with an electronically tunable integrator (ETI) to implement the quadrature oscillator (QO). Experimental responses on the voltage tunable phase of the filter and the linear-tuning law of the quadrature oscillator up to 9.9 MHz at low THD are verified by simulation and hardware tests

Controller implementation using analog reconfigurable hardware (FPAA)

This Thesis has the main target to make a research about FPAA/dpASPs devices and technologies applied to control systems. These devices provide easy way to emulate analog circuits that can be reconfigurable by programming tools from manufactures and in case of dpASPs are able to be dynamically reconfigurable on the fly. It is described different kinds of technologies commercially available and also academic projects from researcher groups. These technologies are very recent and are in ramp up development to achieve a level of flexibility and integration to penetrate more easily the market. As occurs with CPLD/FPGAs, the FPAA/dpASPs technologies have the target to increase the productivity, reducing the development time and make easier future hardware reconfigurations reducing the costs. FPAA/dpAsps still have some limitations comparing with the classic analog circuits due to lower working frequencies and emulation of complex circuits that require more components inside the integrated circuit. However, they have great advantages in sensor signal condition, filter circuits and control systems. This thesis focuses practical implementations of these technologies to control system PID controllers. The result of the experiments confirms the efficacy of FPAA/dpASPs on signal condition and control systems.Esta tese tem como principal objectivo fazer uma pesquisa sobre circuitos integrados e tecnologias das FPAA/dpASPs aplicadas a sistemas de controlo. Estes dispositivos possibilitam a emulação de circuitos analógicos que podem ser reconfiguráveis por ferramentas de programação dos próprios fabricantes e no caso dos dpASPs são capazes de ser dinamicamente reconfiguráveis em tempo real. São descritas diferentes tecnologias disponíveis no mercado e também projectos académicos de grupos de investigação. Estas tecnologias são muito recentes e estão em pleno desenvolvimento para alcançar um nível de flexibilidade e integração para penetrar mais facilmente no mercado. Como já ocorre com as CPLD/FPGAs, os FPAA/dpASPs tem o objectivo de aumentar a produtividade, reduzindo o tempo de desenvolvimento e facilitar reconfigurações futuras de hardware, reduzindo os custos. As FPAA/dpASPs ainda tem algumas limitações comparando com os circuitos analógicos clássicos devido a uma menor largura de banda de frequências de trabalho e à dificuldade de emulação de circuitos complexos que requerem mais componentes dentro do circuito integrado e portanto uma maior escala de integração. No entanto, estes circuitos integrados têm grandes vantagens e podem ser utilizados para aplicações de condicionamento do sinal de sensores, circuitos de filtros e sistemas de controlo. Esta tese concentra-se nas implementações práticas destas tecnologias aos sistemas de controlo usando controladores PID. Os resultados das experiências confirmam a eficácia das FPAA/dpASPs no condicionamento de sinal e sistemas de controlo

0.3-Volt Rail-to-Rail DDTA and Its Application in a Universal Filter and Quadrature Oscillator

This paper presents the extremely low-voltage supply of the CMOS structure of a differential difference transconductance amplifier (DDTA). With a 0.3-volt supply voltage, the circuit offers rail-to-rail operational capability. The circuit is designed for low-frequency biomedical and sensor applications, and it consumes 357.4 nW of power. Based on two DDTAs and two grounded capacitors, a voltage-mode universal filter and quadrature oscillator are presented as applications. The universal filter possesses high-input impedance and electronic tuning ability of the natural frequency in the range of tens up to hundreds of Hz. The total harmonic distortion (THD) for the band-pass filter was 0.5% for 100 mV(pp) @ 84.47 Hz input voltage. The slight modification of the filter yields a quadrature oscillator. The condition and the frequency of oscillation are orthogonally controllable. The frequency of oscillation can also be controlled electronically. The THD for a 67 Hz oscillation frequency was around 1.2%. The circuit is designed and simulated in a Cadence environment using 130 nm CMOS technology from United Microelectronics Corporation (UMC). The simulation results confirm the performance of the designed circuits

CMOS Hyperbolic Sine ELIN filters for low/audio frequency biomedical applications

Hyperbolic-Sine (Sinh) filters form a subclass of Externally-Linear-Internally-Non- Linear (ELIN) systems. They can handle large-signals in a low power environment under half the capacitor area required by the more popular ELIN Log-domain filters. Their inherent class-AB nature stems from the odd property of the sinh function at the heart of their companding operation. Despite this early realisation, the Sinh filtering paradigm has not attracted the interest it deserves to date probably due to its mathematical and circuit-level complexity. This Thesis presents an overview of the CMOS weak inversion Sinh filtering paradigm and explains how biomedical systems of low- to audio-frequency range could benefit from it. Its dual scope is to: consolidate the theory behind the synthesis and design of high order Sinh continuous–time filters and more importantly to confirm their micro-power consumption and 100+ dB of DR through measured results presented for the first time. Novel high order Sinh topologies are designed by means of a systematic mathematical framework introduced. They employ a recently proposed CMOS Sinh integrator comprising only p-type devices in its translinear loops. The performance of the high order topologies is evaluated both solely and in comparison with their Log domain counterparts. A 5th order Sinh Chebyshev low pass filter is compared head-to-head with a corresponding and also novel Log domain class-AB topology, confirming that Sinh filters constitute a solution of equally high DR (100+ dB) with half the capacitor area at the expense of higher complexity and power consumption. The theoretical findings are validated by means of measured results from an 8th order notch filter for 50/60Hz noise fabricated in a 0.35μm CMOS technology. Measured results confirm a DR of 102dB, a moderate SNR of ~60dB and 74μW power consumption from 2V power supply

Analog Reconfigurable Circuits

The aim of this paper is to present an overview of a new branch of analog electronics represented by analog reconfigurable circuits. The reconfiguration of analog circuits has been known and used since the beginnings of electronics, but the universal reconfigurable circuits called Field Programmable Analog Arrays (FPAA) have been developed over the last two decades. This paper presents the classification of analog circuit reconfiguration, examples of FPAA solutions obtained as academic projects and commercially available ones, as well as some application examples of the dynamic reconfiguration of FPAA.

A Universal Amplifier Module (UAM) in 0.18 µm CMOS (CMOSP18/TSMC) Technology With Some Applications in Analog Signal Processing

The amplifiers such as operational amplifier, operational transconductance amplifier, operational transresistance amplifier, current conveyor etc. are the basic building blocks in analog circuits and systems. These important basic amplifiers find wide spread applications in the integration of several electronic systems. However, different analog devices are preferred for different systems. It is difficult to use a single type of device to cater for the needs of different systems with diverse input output impedance environments. In this thesis work, a Universal Amplifier Module (UAM) is designed and implemented in a modern 0.18µm CMOS (CMOSP18/TSMC) technology and its applications toward realization of second order voltage and current – mode filters are reported. Concepts of network transposition and nullor equivalent of ideal active devices are utilized to realize both voltage and current – mode filters using the same UAM module which is able to provide all the voltage and current mode operations (such as, OP-AMP with VCVS, OTA with VCCS, OTRA with CCVS, and CCCS)

A miniature tunable quadrature shadow oscillator with orthogonal control

This article presents a new design of a quadrature shadow oscillator. The oscillator is realized using one input and two outputs of a second-order filter cell together with external amplifiers in a feedback configuration. The oscillation characteristics are controlled via the external gain without disturbing the internal filter cell, following the concept of the shadow oscillator. The proposed circuit configuration is simple with a small component-count. It consists of, two voltage-different transconductance amplifiers (VDTAs) along with a couple of passive elements. The frequency of oscillation (FO) and the condition of oscillation (CO) are controlled orthogonally via the dc bias current and external gain. Moreover, with the addition of the external gain, the frequency range of oscillation can be further extended. The proposed work is verified by computer simulation with the use of 180 nm complementary metal–oxide–semiconductor (CMOS) model parameters. The simulation gives satisfactory results of two sinusoidal output signals in quadrature with some small total harmonic distortions (THD). In addition, a circuit experiment is performed using the commercial operational transconductance amplifiers LM13700 as the active components. The circuit experiment also demonstrates satisfactory outcome which confirms the validity of the proposed circuit