Browsing by Author "Monga, Dipesh C."

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  • A Compact Untrimmed 48ppm/°C All MOS Current Reference Circuit
    (2022) Monga, Dipesh C.; Halonen, Kari
     A4 Artikkeli konferenssijulkaisussa
    An ultra-low power and low-cost (area efficient) nano-Ampere current reference circuit designed in a 65 nm technology is presented in this paper: The proposed circuit is a resistorless beta multiplier current reference circuit that uses self cascode composite MOSFETs in triode region. Circuit analysis has been discussed in the paper. The simulated circuit consumes power of 550 nW at a nominal operating voltage of 1.33 V and occupies area of 0.0031 mm2. The design provides a line regulation of 1.9 %/V over an operating voltage range of 1.25 V to 1.4 V. Temperature coefficient (TC) of the circuit at nominal voltage of 1.33 V is 48 ppm/°C for a wide temperature range of-40°C to 85°C. Output current of the circuit at nominal voltage is 104.2 nA with a small process variation of only 4 %.
  • Flexible RF to DC Converter for Wireless Power Transfer in NFC and Biomedical Systems
    (2024) Monga, Dipesh C.; Halonen, Kari
     A4 Artikkeli konferenssijulkaisussa
    To facilitate the versatile use of flexible energy harvesters, this work discusses the design and characterization of a novel radio frequency (RF) to DC converter built in indium gallium zinc oxide (IGZO) thin film transistor (TFT) technology, developed to meet the energy requirements of near-field communication (NFC) and biomedical applications. The design uses a hybrid topology that combines the efficiency of a cross-coupled converter with the voltage-enhancing capabilities of Dickson charge pumps. This converter is designed to address the challenges of variable RF environments because of its dynamic adjustment technique involving self-biasing resistors and gate voltage-boosting capacitors. The circuit is implemented in a 600 nm TFT technology, and post-layout simulations verify that the circuit can achieve a peak power conversion efficiency (PCE) of 41.5 % at a load resistance of 906 kΩ and exhibiting sensitivity levels as low as -20 dBm. The compact area of 0.0127 mm2 gives this circuit the potential for integration into disposable NFC tags and single-use biomedical devices where efficiency, size, and cost are key factors.
  • Smart Diaper with Printed Capacitive Sensors and Integrated Front-end to Monitor Voided Fluid Volume
    (2024-05-01) Tanweer, Muhammad; Monga, Dipesh C.; Gillan, Liam; Sepponen, Raimo; Oguz Tanzer, I.; Halonen, Kari A.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    As the demographic structure of the global population continues to shift toward an aging population, caregivers encounter formidable obstacles in detecting wetness events and assessing the quantity of voided volume within diapers. Nevertheless, the integration of electronics with diapers, frequent removal and reapplication, and battery management still pose practical challenges. In this study, a solution of carbon- and silver-printed flexible capacitive sensors interfaced with a custom-designed application-specific integrated circuit (ASIC) is proposed to detect urination events and estimate voided volumes in diapers. A power-optimized application-specific front-end interface circuit is developed to enhance power efficiency and reduce battery maintenance. The circuit is designed to support power-harvesting-based operations and to reduce reliance on external sources, consuming a maximum power of 3.05 mu text{W}. In vitro measurements validate on-chip electronics functionality and sensor performance to detect and quantify voided fluid volume as low as 50 mL. The promising results pave the way for cost-effective, disposable solutions in smart diapers. The proposed solution improves efficiency and comfort for both caregivers and elderly individuals.
  • A Sub-nW Temperature Invariant Voltage Reference in a Unipolar TFT-based Flexible IC Technology
    (2024) Monga, Dipesh C.; Halonen, Kari
     A4 Artikkeli konferenssijulkaisussa
    Voltage reference circuits are crucial for any mixed-signal circuits, providing PVT (Process, Voltage, Temperature) robust output for the system's stability and accuracy. This paper presents a novel voltage reference circuit implemented in an indium gallium zinc oxide (IGZO) based thin film transistors (TFT) technology, proposing for the first time a sub-nanowatt, area-efficient circuit realized with only a single N-type TFT in a 600 nm technology. The design occupies a minimal area of 27x37 μm2, operates across a broad supply voltage range from 0.5 V to 3 V, and maintains functionality from 0 °C to 100 °C. The circuit has an ultra-low power consumption between 0.75 nW to 1.2 nW while achieving an output voltage of 454 mV with a temperature coefficient (TC) as low as 28.9 ppm/°C. The simulated results, which include process variation, temperature dependence, line sensitivity and power supply rejection ratio measurements, underline the circuit's potential for high-efficiency, low-power applications in next-generation flexible electronics.
  • A temperature and process compensation circuit for resistive-based in-memory computing arrays
    (2023) Monga, Dipesh C.; Numan, Omar; Andraud, Martin; Halonen, Kari
     A4 Artikkeli konferenssijulkaisussa
    In-Memory Computing (IMC) architectures promise increased energy-efficiency for embedded artificial intelligence. Many IMC circuits rely on analog computation, which is more sensitive to process and temperature variations than digital. Thus, maintaining a suitable computation accuracy may require process and temperature compensation. Focusing on resistive-based IMC architectures, we propose an ultra-low power circuit to compensate for the temperature and process-based non-linearities of resistive computing elements. The proposed circuit, implemented in 65 nm CMOS can provide a temperature coefficient between 10 and 1938 ppm/°C for a wide temperature range (-40°C to 80°C) and output current range (few pA up to 600 nA) at 1.2 V operating voltage. Used in a resistive IMC array, the variation of output currents from each multiply-accumulate (MAC) operation can be reduced by up to 84% to maintain computation accuracy across process and temperature variations.
  • Ultra-Low-Power Front-end Design on Flexible IC Technology for Capacitive Sensors
    (2024) Tanweer, Muhammad; Monga, Dipesh C.; Halonen, Kari
     A4 Artikkeli konferenssijulkaisussa
    This paper presents an application-specific integrated circuit (ASIC) front-end, to interface the printed capacitive sensors, using an amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) thin film transistors (TFT) on flexible integrated circuit (FlexIC) technology. A ring oscillator (RO) based front-end sensor interface is designed with 0.024 mm2 area using 600 nm channel length of n-type TFTs consuming 183 nW at a supply voltage of 1 V. It generates output frequency sensitive to the change in the input capacitance of the printed coplanar sensor introduced by the moisture variations. Measurement results show that the front-end ASIC can detect the change in capacitance from 10 pF up to 500 pF of the printed coplanar sensor making it suitable not only for moisture detection but also for the evaluation of voided liquid volumes inside diapers to realize economical, disposable and battery-less Internet of Things (IoT) sensor nodes using green energy harvested from urine.