An electrocardiogram readout circuit based on CMOS operational floating current conveyor

Electrocardiogram (ECG) is used in diagnosing heart diseases. It is designed as integration between current-mode instrumentation amplifiers (CMIA) and low pass filter (LPF). Normal heart behavior can be identified simply by normal ECG that consists of signal while heart disorder can be recognized by having differences in the features of their corresponding ECG waveform. A novel integrated CMOS-based operational floating current conveyor (OFCC) circuit is proposed. OFCC is a five port general purpose analog building block which combines all the features of different current mode devices such as the second generation current conveyor (CCII), the current feedback operational amplifier (CFA), and the operational floating conveyor (OFC). The OFFC is modeled and simulated using UMC 130nm CMOS technology kit in Cadence with a supply voltage 1.2V. The ECG readout circuit has been designed using the proposed OFCC as a building block. The advantages of this: it is integrated, noise factor is small as the proposed OFCC has the lowest input noise voltage and the layout is simple as it is a single block that can be repeated several times

Current-Feedback Amplifiers Design using 0,35 µm CMOS Technologie

Orientador: Carlos Alberto dos Reis FilhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Este trabalho apresenta o estudo aprofundado e a confecção de amplificadores realimentados por corrente (CFA). São analisadas as principais características de um CFA e comparado com o amplificador realimentado por tensão (VOA). Buscou-se esclarecer as aplicações nas quais a primeira célula apresenta-se como melhor alternativa e como importante ferramenta a ser disponibiliza aos projetistas. Ao longo desta analise são frisadas as principais dificuldades na implementação da célula em tecnologia CMOS mencionando as soluções encontradas pela na literatura. Estas dificuldades impedem a confecção de CFAs CMOS comerciais. Um dos principais problemas da implementação de amplificadores realimentados por corrente em tecnologia CMOS e a baixa transcondutância dos transistores. A literatura propõe contornar esta deficiência da tecnologia utilizando células que obtêm alta transcondutância através do uso de realimentação interna [1]. Entretanto, a topologia proposta possui um severo compromisso entre transcondutância e banda de freqüência. O trabalho apresentado nesta dissertação deixa sua contribuição a literatura propondo dois métodos para amenizar este compromisso, que resultam no deslocamento da freqüência de -3dB, tornando-a significantemente maior que a original. No exemplo de projeto, aqui ilustrado, foi obtida banda 3,25 vezes a original,mantendo as características DC.O projeto de duas topologias, sendo uma baseada no primeiro CFA monolítico comercializado e a outra que utiliza transistores compostos, foi realizado visando a implementação monolítica em tecnologia 0,35 ?m CMOS da fabrica Austriamicrosystems. Os protótipos fabricados foram medidos e os resultados comparados com o esperado por simulaçãoAbstract: This work presents the study and design of current-feedback amplifiers (CFA).It is analyzed the main characteristics of a CFA as it compares to a typical voltage feedback amplifier (VOA). It was attempted to clarify in which applications the first mentioned cell excels at and why it can serve as an important tool for the designers. Throughout the analysis, the main difficulties regarding the implementation of the cell using CMOS technology are highlighted and the solutions proposed by the literature exposed. Those characteristics restrain the conception of CMOS commercials CFAs. One of the primary obstacles for the implementation of current-feedback amplifiers using CMOS technology is the low transconductance of the transistors. The literature proposes the use of cells with internal feedback in order to solve this issue [1].However, the proposed cell has a severe trade-off between transconductance and frequency bandwidth. This work provides its contribution to the literature by proposing two methods to loosen this trade-off. Using the proposed modification, it was obtained 3.25 times the original bandwidth while maintaining all of its native DC characteristics. The design of two topologies was carried out using monolithic Austriamicrosystems0.35?m CMOS technology; one based on the topology of the first commercialized monolithic CFA and the other using compound transistors. The produced prototypes were measured and the results compared with expected by simulationMestradoEletrônica, Microeletrônica e OptoeletrônicaMestre em Engenharia Elétric