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Reconfigurable Voltage-Mode First-Order Multifunction Filter Employing Second-Generation Voltage Conveyor (VCII) With Complete Standard Functions and Electronically Controllable Modification
(IEEE, 2023-06-05) Jaikla, Winai; Sangyaem, Surasak; Supavarasuwat, Piya; Khateb, Fabian; Minaei, Shahram; Kulej, Tomasz; Suwanjan, Peerawut
In this contribution, the realization of a first-order, two-input, single-output voltage-mode multifunction filter employing a second-generation voltage conveyor (VCII) is described. The proposed first-order versatile filter is extremely simple, composed of a single VCII and three passive devices. Because of its low output impedance, the output voltage node can be easily cascaded with other voltage-mode configurations without the requirement of any buffers. In the same circuit topology, the proposed firstorder filter provides various filtering functions: inverting and non-inverting low-pass (LPF), inverting and non-inverting high-pass (HPF), as well as inverting and non-inverting all-pass (APF). The digital method allows the selection of output first-order filtering functions without the need for additional circuits such as inverting or double-gain amplifiers. Furthermore, the pass-band gain of the low-pass and high-pass responses can be adjusted by varying the resistance or capacitance values without influencing the pole frequency as well as the phase response. The influence of VCII's current/voltage gain errors and parasitic elements on filtering performance is also investigated. Moreover, the modification of the proposed lagging phase allpass filter to achieve electronic controllability is also proposed by replacing the passive resistor with the operational transconductance amplifier (OTA). The 0.18 mu mTSMCCMOSstructure of the VCII employed in the proposed filter operates in the subthreshold region and utilizes the bulk-driven technique (BD), enabling it to operate with 0.4V supply voltage and consuming 383 nW of power. The total harmonic distortion (THD) of the LPF with an applied input voltage V-inpp =300mV @ 50Hz is -49.5 dB. An application example as a quadrature sinusoidal oscillator realized from the proposed first-order allpass filter and lossless integrator is also included. The performance of the proposed reconfigurable voltage-mode first-order filter is simulated and experimentally tested using a commercially available AD844 IC-based VCII with +/- 5 V power supply.
31.3 nW, 0.5 V Bulk-Driven OTA for Biosignal Processing
(IEEE, 2023-05-24) Kumngern, Montree; Kulej, Tomasz; Khateb, Fabian
This paper presents a new extremely low-voltage low-power bulk-driven (BD) operational transconductance amplifier (OTA) realized for low frequency biosignal processing. The CMOS structure of the OTA utilizes bulk-driven and self-cascode techniques in the subthreshold region, supporting the operation with the supply voltage (V-DD) as the threshold voltage (V-TH) of a single MOS transistor, i.e., V-DD = V-TH = 0.5 V, while offering nano power consumption (31.3 nW for 15 nA nominal setting current). Using the extremely low-voltage and low-power OTA in biosignal processing enables extending the lifetime of applications that are powered by battery or energy harvesting sources. The OTA has a 54.7 dB low frequency gain, 6.18 kHz gain bandwidth and 75 degrees phase margin at 15 pF load capacitance. The proposed OTA has been used to realize a bandpass filter (BPF) with adjustable gain for electrocardiogram (ECG) signal processing. The higher cutoff frequency of the BPF is adjustable electronically by a setting current and the BPF's gain can be adjusted by capacitors value. The total harmonic distortion (THD) of the BPF is -53.56 dB, the input integrated input-referred voltage noise is 17.9 mu V-rms, the common mode rejection ratio (CMRR) is 75 dB and the power supply rejection ratio (PSRR) is 87.7 dB. The BPF was designed in the Cadence program using 0.18 mu m CMOS technology from TSMC. The simulation results agree with the presented theory.
Contrast enhanced X-ray computed tomography imaging of amyloid plaques in Alzheimer disease rat model on lab based micro CT system
(Springer Nature, 2021-03-16) Kavková, Michaela; Zikmund, Tomáš; Kala, Annu; Šalplachta, Jakub; Lissette Proskauer Pena, Stephanie; Kaiser, Jozef; Ježek, Karel
Amyloid plaques are small (similar to 50 mu m), highly-dense aggregates of amyloid beta (A beta) protein in brain tissue, supposed to play a key role in pathogenesis of Alzheimer's disease (AD). Plaques' in vivo detection, spatial distribution and quantitative characterization could be an essential marker in diagnostics and evaluation of AD progress. However, current imaging methods in clinics possess substantial limits in sensitivity towards A beta plaques to play a considerable role in AD screening. Contrast enhanced X-ray micro computed tomography (micro CT) is an emerging highly sensitive imaging technique capable of high resolution visualization of rodent brain. In this study we show the absorption based contrast enhanced X-ray micro CT imaging is viable method for detection and 3D analysis of A beta plaques in transgenic rodent models of Alzheimer's disease. Using iodine contrasted brain tissue isolated from the Tg-F344-AD rat model we show the micro CT imaging is capable of precise imaging of A beta plaques, making possible to further analyze various aspects of their 3D spatial distribution and other properties.
X-ray microtomography–based atlas of mouse cranial development
(Oxford University Press, 2021-03-02) Matula, Jan; Kaiser, Markéta; Zikmund, Tomáš; Kaucká, Markéta; Adameyko, Igor; Kaiser, Jozef
X-ray microtomography (CT) has become an invaluable tool for non-destructive analysis of biological samples in the field of developmental biology. Mouse embryos are a typical model for investigation of human developmental diseases. By obtaining 3D high-resolution scans of the mouse embryo heads, we gain valuable morphological information about the structures prominent in the development of future face, brain, and sensory organs. The development of facial skeleton tracked in these CT data provides a valuable background for further studies of congenital craniofacial diseases and normal development. In this work, reusable tomographic data from 7 full 3D scans of mouse embryo heads are presented and made publicly available. The ages of these embryos range from E12.5 to E18.5. The samples were stained by phosphotungstic acid prior to scanning, which greatly enhanced the contrast of various tissues in the reconstructed images and enabled precise segmentation. The images were obtained on a laboratory-based CT system. Furthermore, we provide manually segmented masks of mesenchymal condensations (for E12.5 and E13.5) and cartilage present in the nasal capsule of the scanned embryos. We present a comprehensive dataset of X-ray 3D computed tomography images of the developing mouse head with high-quality manual segmentation masks of cartilaginous nasal capsules. The provided CT images can be used for studying any other major structure within the developing mouse heads. The high quality of the manually segmented models of nasal capsules may be instrumental to understanding the complex process of the development of the face in a mouse model.
0.5 V, nW-Range Universal Filter Based on Multiple-Input Transconductor for Biosignals Processing
(MDPI, 2022-11-08) Khateb, Fabian; Kumngern, Montree; Kulej, Tomasz; Akbari, Meysam; Stopjaková, Viera
This paper demonstrates the advantages of the multiple-input transconductor (MI-G(m)) in filter application, in terms of topology simplification, increasing filter functions, and minimizing the count of needed active blocks and their consumed power. Further, the filter enjoys high input impedance, uses three MI-G(m)s and two grounded capacitors, and it offers both inverting and non-inverting versions of low-pass (LPF), high-pass (HPF), band-pass (BPF), band-stop (BS) and all-pass (AP) functions. The filter operates under a supply voltage of 0.5 V and consumes 37 nW, hence it is suitable for extremely low-voltage low-power applications like biosignals processing. The circuit was designed in a Cadence environment using 180 nm CMOS technology from Taiwan Semiconductor Manufacturing Company (TSMC). The post-layout simulation results, including Monte Carlo and process, voltage, temperature (PVT) corners for the proposed filter correlate well with the theoretical results that confirm attractive features of the developed filter based on MI-G(m).

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