ENIDH – EEM - Engenharia Eletrotécnica Marítima
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Browsing ENIDH – EEM - Engenharia Eletrotécnica Marítima by Subject "Biomedical"
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- A new family of CMOS inverter based OTAs for Biomedical and Healthcare ApplicationsPublication . Póvoa, Ricardo; Canelas, António; Martins, Ricardo; Lourenço, Nuno; Horta, Nuno; Goes, JoãoThis paper presents a new family of innovative operational transconductance amplifier (OTA) topologies based on CMOS inverter structures, with improved gain and energy-efficiency. This new family of OTA designs is suitable for biomedical and healthcare circuits and systems, due to the high energy-efficiency, improved gain and low level of noise contribution, when compared to the state-of-the-art in this field. In this paper, two fully-differential implementations are presented, a first one with a double CMOS branch biased by two pairs of voltage-combiners structures in both NMOS and PMOS configurations, and a second one with folded voltage-combiners specifically targeting low voltage applications, e.g., supplies below 1 V. The usage of voltage-combiners to bias the OTAs improves the gain and the gain-bandwidth product, therefore improving the energy-efficiency figure-of-merit. High values of figure-of-merit are achieved in both implementations, i.e., more than 1600 MHz × pF/mA and 2000 MHz × pF/mA, gain values above 53 dB and 50 dB under supply sources of 2 V and 0.7 V respectively. The folded voltage-combiners biased OTA is able to operate correctly under a voltage supply down to 0.7 V with proper DC biasing. The results are finally compared with state-of-the-art in this field and the potential of the circuits is fulfilled using a state-of-the-art layout-aware integrated-circuit optimization framework, AIDA, particularly relevant in order to overcome the device stacking problematic for lower voltages.
- Sub- μW Tow-Thomas Based Biquad Filter with Improved Gain for Biomedical ApplicationsPublication . Póvoa, R.; Arya, R.; Canelas, A.; Passos, F.; Martins, R.; Lourenço, N.; Horta, N.This paper presents an innovative topology of a gm-C Operational Transconductance Amplifier (OTA), with improved gain and energy-efficiency and its corresponding implementation inside a second order Tow-Thomas based filter configuration, for biomedical and healthcare applications. The proposed OTA architecture takes advantage of a current division technique, as well as the usage of a pair of cross-coupled voltage-combiners in replacement of the static current source that traditionally bias the differential pair. The circuitry proposed in this paper is described at analytical level, fully-designed at sizing level and validated at simulation level compounded by Monte Carlo results, using a standard 130 nm technology node. Both the OTA and the biquad filter architecture are compared, in terms of performance indexes, with state-of-the-art bibliography, where the potential of both is demonstrated. The designed filter operates at weak inversion and sub-threshold, being supplied by a 0.9 V source, achieving a cut-off frequency of 15 Hz, a gain of 7 dB, hence improving the input-referred noise and consuming nearly 0.55 μW.
- A Sub-1 µA Low-Power, LowNoise Amplifier with Tunable Gain and Bandwidth for EMG and EOG Biopotential SignalsPublication . Vieira, Rafael; Martins, Ricardo; Horta, Nuno; Lourenço, Nuno; Póvoa, RicardoThis paper presents the design of a low-power low-noise amplifier for biomedical and healthcare applications, focusing on electromyography and electrooculography. The signals operate in different broad bands, yet follow an impulse-shape transmission, being suitable to be applied and detected by the same receiver. The biopotential sensing amplifiers usually have a major impact in power and noise performance of an analog front end; hence, the development of a low-noise amplifier with low-power consumption is of great importance. In this paper, the state-of-the-art amplifiers for biomedical applications are overviewed, and the proposed solution is presented. The proposed design has tunable cutoff frequency (FC) and gain, being adjustable for each type of signal. The circuit is designed in UMC 130 nm CMOS technology, supplied by 1.2 V, and consumes less than 1 μA. Post-layout simulation results show that, at the high FC of 2 kHz, the gain is 34 dB, presenting an input-referred noise of 1.476 μVrms corresponding to a noise efficiency factor (NEF) of 1.27. Whereas at the low FC of 20.91 Hz, the gain is 52.35 dB, the input-referred noise is 0.202 μVrms, and the NEF is 1.70.