1,412 research outputs found
Temperature Compensation of Crystal References in NB-IoT Modems
No full textThe low-cost nature of NB-IoT modems encourages them to deploy uncompensated crystal oscillators (XOs) as frequency references. The frequency offset of an uncompensated XO, however, makes network acquisition inefficient under low network coverage. In the worst case, the bulk of an NB-IoT modem's power is consumed in network acquisition. This work demonstrates a discrete frequency synthesizer prototype that employs its phase-locked loop to compensate for the frequency offset of its reference XO. We propose an accurate crystal model and a compensation logic that are suitable for 32-bit microprocessors, commonly available in NB-IoT modems. Alternatively, when synthesized in a commercial 65-nm process in 24-bit precision, the proposed compensation logic is simulated to require a total area of 0.029 mm2 and power of 290 nW at a refresh rate of 1.4 kHz. Moreover, the XO model requires only 0.16 kB of RAM. The prototype achieves a compensation error level of down to 27 ppb (3Σ) over the temperature range from-40 to 85 °C. The dominant error sources of the prototype are discussed in detail. In addition, we show that an NB-IoT modem can use the information acquired from sequential network acquisitions to compose and update its XO model in the field. This support for field calibration removes the need for XO characterization in production and ensures the validity of the model over the NB-IoT modem's lifespan. The prototype achieves a compensation error level of down to 50 ppb (3Σ) in an emulated in-field calibration test, sufficient to ensure energy-efficient low-latency network acquisition under low network coverage.Peer reviewe
A Fully Integrated Digitally Programmable Pulse Shaping 6.0-8.5 GHz UWB IR Transmitter Front-End for Energy Harvesting Applications
No full textThis paper presents a fully integrated ultra-wideband impulse radio transmitter front-end (TFE) that is compliant with the European spectral mask. The compliance is achieved by means of 4-bit digital pulse shaping and an integrated matching network. The center frequency of the TFE is digitally tunable with 24 MHz resolution between 6.5-8.0 GHz. The TFE delivers at least 2.0 pJ pulses over the whole frequency range and achieves 4.4 % efficiency at 7.5 GHz center frequency and 4 MHz pulse repetition rate. The static power consumption is 480 nW, which enables the TFE to reach high efficiency levels even at low pulse repetition rates. The TFE is designed in a commercial 65-nm CMOS process. The performance of the TFE is evaluated through post-layout simulations.Peer reviewe
A 40 nW CMOS-based temperature sensor with calibration free inaccuracy within ±0.6◦c
No full textIn this study, a temperature equivalent voltage signal was obtained by subtracting output voltages received from two individual temperature sensors. These sensors work in the subthreshold region and generate the output voltage signals that are proportional and complementary to the temperature. Over the temperature range of −40◦C to +85◦C without using any calibration method, absolute temperature inaccuracy less than ±0.6◦C was attained from the measurement of five prototypes of the proposed temperature sensor. The implementation was done in a standard 0.18 µm CMOS technology with a total area of 0.0018 mm2. The total power consumption is 40 nW for a supply voltage of 1.2 V measured at room temperature.Peer reviewe
Outlooks on Transmitter Energy Efficiency and FOM and a −189.7-dBJ/bit ULP DPPM Transmitter
No full textPublisher Copyright: AuthorIn this paper, we compare in a new way the energy efficiencies of modulations that have been popular in ultra-low power (ULP) transmitters. The comparison considers how the choice of modulation affects the combined energy consumed per bit (EPB) by the carrier synthesizer and power amplifier (PA). The comparison includes on-off keying (OOK), binary phase-shift keying (BPSK), binary frequency-shift keying (BFSK), pulse-position modulation (PPM) and differential PPM (DPPM). The results suggest that using OOK, BPSK or BFSK can consume tens to hundreds of percents more energy per bit compared to PPM and DPPM. Furthermore, a new energy efficiency figure of merit (FOM) is derived for transmitters. It accounts for consumed power, output power, data rate, signal bandwidth and signal-to-noise ratio required by the utilized modulation. The FOM can be applied to various types of transmitters with numerous modulations. We also present a sub-100 W DPPM transmitter (TX) and a 3.2- W 2-axis gesture sensor interface, implemented in 0.18 m CMOS. The TX operates in the 433-MHz band, uses pulse shaping for improved spectrum and achieves a FOM of 189.7 dBJ/bit. The estimated uplink range is up to 1 kilometerPeer reviewe
A Compact Untrimmed 48ppm/°C All MOS Current Reference Circuit
No full textFunding Information: The authors are grateful to Academy of Finland for funding this work under the project EHIR (Wireless impulse radio data link powered by energy harvesting). Publisher Copyright: © 2022 IEEE.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 %.Peer reviewe
Low-Power Wireless Transceiver with 67-nW Differential Pulse-Position Modulation Transmitter
No full textThis article presents a low-power wireless narrowband (NB) transceiver consisting of a 434-MHz NB transmitter (NBTX) and a 434-MHz NB receiver (NBRX) implemented in 0.18 μ m CMOS. The NBTX utilizes differential pulse-position modulation (DPPM) to decrease consumed energy per bit (EPB) by up to 67% compared to on-off keying (OOK). The packet error performance of DPPM with a soft-decision decoding scheme is analyzed. According to the results, the packet error ratio (PER) does not deteriorate compared to OOK except at very low signal-to-noise levels. The lowest power consumption of the NBTX is 8.3 μ W when DPPM data is transmitted continuously. Utilizing packet-mode transmission, the average power consumption is 67 nW at a data rate of 4.8 kbps. The transmitted data was received with a PER of 0.1% by a receiver placed at a 30-meter distance from the NBTX. With a higher power consumption of 2.5 μ W at the same data rate, the estimated line-of-sight (LOS) uplink range is up to 200 meters. The NBRX is a mixer-firstuncertain-IF receiver. A temperature-compensated ring oscillator (TCRO) is utilized as a local oscillator. Its measured deviation of frequency is from +0.1% to -1.2% over a temperature range from -40 to +85 °C. The NBRX utilizes Manchester encoding and the sensitivity is -87 to -82 dBm over the temperature range at a data rate of 40 kbps. The NBRX consumes 85 μ W.Peer reviewe
Flexible RF to DC Converter for Wireless Power Transfer in NFC and Biomedical Systems
No full textPublisher Copyright: © 2024 IEEE.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.Peer reviewe
A Sub-nW Temperature Invariant Voltage Reference in a Unipolar TFT-based Flexible IC Technology
No full textPublisher Copyright: © 2024 IEEE.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.Peer reviewe
Development of wearable hardware platform to measure the ECG and EMG with IMU to detect motion artifacts
No full textWeareable biomedical devices make it possible to monitor physiological parameters of human beings where physical fitness is critical for their work. However, the motion artifacts corrupt the ambulatory measurements of electrophysiological parameters and it is necessary to detect and eliminate these motion artifacts. The long term measurement and analysis of health parameters require enormous data processing and storage resources on board. It is also challenging to perform sensor fusion of multiple devices and to manage multiple communication channels. This paper describes the development of a wearable hardware platform to measure electrocardiogram (ECG) and electromyogram (EMG) with an additional IMU sensor to detect the motion artifacts. Bringing all the sensors on single platform resolves the sensor fusion problems. The measurements are digitized and sent wirelessly through a bluetooth interface to a remote unit in real-time. Which is capable for the implementation of extensive processing and analysis algorithms to detect the motion artifacts and extract The features of ECG and EMG waveform structures.Peer reviewe
A 180-nW static power UWB IR transmitter front-end for energy harvesting applications
No full textThis paper presents a versatile, FCC compliant ultra-wideband impulse radio transmitter front-end (TFE) that performs well at a wide range of pulse repetition rates up to 105 MHz. The TFE delivers 2.2 pJ pulses with 6.7 % efficiency at 3.8 GHz center frequency. The leakage power is 180 nW from a 1.2 V supply. The TFE operates robustly with a variety of power sources, including a 6.5 cm2 photovoltaic array in office illumination. Along with the low static power consumption level, this feature makes the TFE suitable for energy harvesting applications. The TFE is fabricated in a 180 nm CMOS process.Peer reviewe
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