On the Design of Voltage-Controlled Sinusoidal Oscillators Using OTA's

A unified systematic approach to the design of voltage-controlled oscillators using only operational transconductance amplifiers (OTA's) and capacitors is discussed in this paper. Two classical oscillator models, i.e., quadrature and bandpass-based, are employed to generate several oscillator structures. They are very appropriate for silicon monolithic implementations. The resulting oscillation frequencies are proportional to the transconductance of the OTA and this makes the reported structures well-suited for building voltage controlled oscillators (VCO's). Amplitude stabilization circuits using both automatic gain control (AGC) mechanisms and limitation schemes are presented which are compatible with the transconductance amplifier capacitor oscillator (TACO). Experimental results from bipolar breadboard and CMOS IC prototypes are included showing good potential of OTA-based oscillators for high frequency VCO operation.Comisión Interministerial de Ciencia y Tecnología ME87-000

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

CMOS OTA-C high-frequency sinusoidal oscillators

Several topology families are given to implement practical CMOS sinusoidal oscillators by using operational transconductance amplifier-capacitor (OTA-C) techniques. Design techniques are proposed taking into account the CMOS OTA's dominant nonidealities. Building blocks are presented for amplitude control, both by automatic gain control (AGC) schemes and by limitation schemes. Experimental results from 3- and 2- mu m CMOS (MOSIS) prototypes that exhibit oscillation frequencies of up to 69 MHz are obtained. The amplitudes can be adjusted between 1 V peak to peak and 100 mV peak to peak. Total harmonic distortions from 2.8% down to 0.2% have been measured experimentally.Comisión Interministerial de Ciencia y Tecnología ME87-000

A wideband linear tunable CDTA and its application in field programmable analogue array

This document is the Accepted Manuscript version of the following article: Hu, Z., Wang, C., Sun, J. et al. ‘A wideband linear tunable CDTA and its application in field programmable analogue array’, Analog Integrated Circuits and Signal Processing, Vol. 88 (3): 465-483, September 2016. Under embargo. Embargo end date: 6 June 2017. The final publication is available at Springer via https://link.springer.com/article/10.1007%2Fs10470-016-0772-7 © Springer Science+Business Media New York 2016In this paper, a NMOS-based wideband low power and linear tunable transconductance current differencing transconductance amplifier (CDTA) is presented. Based on the NMOS CDTA, a novel simple and easily reconfigurable configurable analogue block (CAB) is designed. Moreover, using the novel CAB, a simple and versatile butterfly-shaped FPAA structure is introduced. The FPAA consists of six identical CABs, and it could realize six order current-mode low pass filter, second order current-mode universal filter, current-mode quadrature oscillator, current-mode multi-phase oscillator and current-mode multiplier for analog signal processing. The Cadence IC Design Tools 5.1.41 post-layout simulation and measurement results are included to confirm the theory.Peer reviewedFinal Accepted Versio

A precise 90º quadrature OTA-C oscillator tunable in the 50-130-MHz range

We present a very-large-scale integration continuous-time sinusoidal operational transconductance amplifiers quadrature oscillator fabricated in a standard double-poly 0.8-μm CMOS process. The oscillator is tunable in the frequency range from 50 to 130 MHz. The two phases produced by the oscillator show a low-quadrature phase error. A novel current-mode amplitude control scheme is developed that allows for very small amplitudes. Stability of the amplitude control loop is studied as well as design considerations for its optimization. Experimental results are provided

A Versatile Active Block: DXCCCII and Tunable Applications

The study describes dual-X controlled current conveyor (DXCCCII) as a versatile active block and its application to inductance simulators for testing. Moreover, the high pass filter application using with DXCCCII based inductance simulator and oscillator with flexible tunable oscillation frequency have been presented and simulated to confirm the theoretical validity. The proposed circuit which has a simple circuit design requires the low-voltage and the DXCCCII can also be tuned in the wide range by the biasing current. The proposed DXCCCII provides a good linearity, high output impedance at Z terminals, and a reasonable current and voltage transfer gain accuracy. The proposed DXCCCII and its applications have been simulated using the CMOS 0.18 µm technology

Current Gain Controlled CCTA and its Application in Quadrature Oscillator and Direct Frequency Modulator

A modified conception of adjustable current conveyor transconductance amplifier (CCTA) and its interesting application in simple quadrature oscillator expandable for direct frequency modulation purposes, employing only four grounded passive elements is presented in this paper. It is quite simple solution for modern communication subsystem components. An electronic adjusting of the oscillation frequency is easily possible and control of condition of the oscillation is realized via only one grounded resistor. The characteristic equation, condition of oscillation and major parasitic influences of real active part are discussed. The verification includes PSpice simulation and measurement with the CCTA block formed by commercially available active elements

Theory of phaselock techniques as applied to aerospace transponders

Phaselock techniques as applied to aerospace transponder

Study of a signal processor employing a synthetic phase isolator

Evaluation of signal data processor employing synthetic phase isolator techniqu

Um amplificador de transimpedância de ganho variável para aplicação em osciladores baseados em MEMS

Orientador: José Alexandre DinizDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Um amplificador de transimpedância (TIA) de ganho variável é apresentado. Implementado em tecnologia 0,18 'mi'm, o projeto relatado possui a finalidade de prover um amplificador de sustentação para osciladores baseados em ressonadores do tipo MEMS (Micro-Electro-Mechanical System). Entre outros, as peculiaridades de projeto envolvem um desafiante compromisso entre Ganho, Largura de Banda, Ruído e Consumo de potência. Sendo assim, o amplificador foi implementado através do cascateamento de quatro estágios de ganho similares, lançando-se mão de realimentação do tipo shunt-shunt para diminuir as impedâncias de entrada e saída. Através do emprego de um estágio de ganho variável, uma alta faixa dinâmica de ganho é alcançada (53 dB), com um ganho máximo de transimpedância de 118 dB'ômega'...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digitalAbstract: A variable gain Transimpedance Amplifier (TIA) is presented. Realized in 0.18 'mi'm technology, this amplifier was conceived with the purpose of providing oscillation sustaining for Micro-Electro-Mechanical System (MEMS) based oscillators. Facing a quite challenging trade-off between Gain, Bandwidth, Noise and Power consumption, the TIA was implemented through the cascade of four similar gain stages, with the application of shunt-shunt feedback to lower both input and output resistances. With the employment of a variable-gain stage, this TIA presents a large gain tunability of 53 dB, with a also large maximum transimpedance gain of 118 dB'omega'...Note: The complete abstract is available with the full electronic documentMestradoEletrônica, Microeletrônica e OptoeletrônicaMestre em Engenharia Elétric