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Percorrer por autor "Vieira, Rafael"

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  • A Sub-1 µA Low-Power, LowNoise Amplifier with Tunable Gain and Bandwidth for EMG and EOG Biopotential Signals
    Publication . Vieira, Rafael; Martins, Ricardo; Horta, Nuno; Lourenço, Nuno; Póvoa, Ricardo
    This paper presents the design of a low-power low-noise amplifier for biomedical and healthcare applications, focusing on lectromyography 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.
    2021-07Atas de conferência Acesso restrito Ver mais
  • A Tunable Gain and Bandwidth Low-Noise Amplifier with 1.44 NEF for EMG and EOG Biopotential Signal
    Publication . Vieira, Rafael; Näf, Fabian; Martins, Ricardo; Horta, Nuno; Lourenço, N.; Póvoa, Ricardo
    This paper presents a low-noise inverter-based current-mode instrumentation amplifier with tunable gain and bandwidth for electromyogram (EMG) and electrooculogram (EOG) biopotential signals, targeting low input noise while maintaining low power consumption. The gain tuning method is based on pseudo-resistors, whereas the bandwidth is tunable due to a varactor system that is controlled by the same control voltage that tunes the gain. The circuit was designed and manufactured using the 110 nm UMC CMOS technology node, occupying an area of 0.624 mm2. The circuit presents a functioning mode for each biopotential signal with different characteristics, for the EMG a gain of 34.7 dB and a bandwidth of 1412 Hz was measured, with an input referred noise of 1.407 μV which matches a noise efficiency factor of 1.44. The EOG mode achieves a 39.5 dB gain and a 22.4 Hz bandwidth while presenting an input-referred noise of 0.829 μV corresponding to a noise efficiency factor of 6.37. For both modes, the supply voltage is 1.2 V and the circuit consumes 1 μA.
    2023-06Contributo em revista Acesso aberto Ver mais
  • Tunable Low-Power Low-Noise Amplifier for Healthcare Applications
    Publication . Vieira, Rafael; Horta, Nuno; Póvoa, Ricardo; Lourenço, Nuno
    This book consists of the research, design and implementation, from sizing to layout with parasitic extraction and yield estimation, of a low-power, low-noise amplifier for biomedical and healthcare applications of bio-potential signals, particularly focusing on the electromyography and electrooculography.
    2021Livro Acesso aberto Ver mais