CMOS ASIC Design of Multi-frequency Multi-constellation GNSS Front-ends

With the emergence of the new global navigation satellite systems (GNSSs) such as Galileo, COMPASS and GLONASS, the US Global Positioning System (GPS) has new competitors. This multiplicity of constellations will offer new services and a much better satellite coverage. Public regulated service (PRS) is one of these new services that Galileo, the first global positioning service under civilian control, will offers. The PRS is a proprietary encrypted navigation designed to be more reliable and robust against jamming and provides premium quality in terms of position and timing and continuity of service, but it requires the use of FEs with extended capabilities. The project that this thesis starts from, aims to develop a dual frequency (E1 and E6) PRS receiver with a focus on a solution for professional applications that combines affordability and robustness. To limit the production cost, the choice of a monolithic design in a multi-purpose 0.18 µm complementary metal-oxide-semiconductor (CMOS) technology have been selected, and to reduce the susceptibility to interference, the targeted receiver is composed of two independent FEs. The first ASIC described here is such FEs bundle. Each FE is composed of a radio frequency (RF) chain that includes a low-noise amplifier (LNA), a quadrature mixer, a frequency synthesizer (FS), two intermediate frequency (IF) filters, two variable-gain amplifiers (VGAs) and two 6-bit flash analog-to-digital converters (ADCs). Each have an IF bandwidth of 50 MHz to accommodate the wide-band PRS signals. The FE achieves a 30 dB of dynamic gain control at each channel. The complete receivers occupies a die area of 11.5 mm2 while consuming 115 mW from a supply of a 1.8 V. The second ASIC that targets civilian applications, is a reconfigurable single-channel FE that permits to exploit the interoperability among GNSSs. The FE can operate in two modes: a ¿narrow-band mode¿, dedicated to Beidou-B1 with an IF bandwidth of 8 MHz, and a ¿wide-band mode¿ with an IF bandwidth of 23 MHz, which can accommodate simultaneous reception of Beidou-B1/GPS-L1/Galileo-E1. These two modes consumes respectively 22.85 mA and 28.45 mA from a 1.8 V supply. Developed with the best linearity in mind, the FE shows very good linearity with an input-referred 1 dB compression point (IP1dB) of better than -27.6 dBm. The FE gain is stepwise flexible from 39 dB and to a maximum of 58 dB. The complete FE occupies a die area of only 2.6 mm2 in a 0.18 µm CMOS. To also accommodate the wide-band PRS signals in the IF section of the FE, a highly selective wide-tuning-range 4th-order Gm-C elliptic low-pass filter is used. It features an innovative continuous tuning circuit that adjusts the bias current of the Gm cell¿s input stage to control the cutoff frequency. With this circuit, the power consumption is proportional to the cutoff frequency thus the power efficiency is achieved while keeping the linearity near constant. Thanks to a Gm switching technique, which permit to keep the signal path switchless, the filter shows an extended tuning of the cutoff frequency that covers continuously a range from 7.4 MHz to 27.4 MHz. Moreover the abrupt roll-off of up to 66 dB/octave, can mitigate out-of-band interference. The filter consumes 2.1 mA and 7.5 mA at its lowest and highest cutoff frequencies respectively, and its active area occupies, 0.23 mm2. It achieves a high input-referred third-order intercept point (IIP3) of up to -1.3 dBVRMS

Design Methodology for Common-Mode Stability of OTA-based Gyrators

This paper presents a design methodology for common-mode (CM) stability of operational transconductance amplifier (OTA)-based gyrators. The topology of gm−C active inductors is briefly reviewed. Subsequently, a comprehensive mathematical analysis on the CM stability of OTA-based gyrators is presented. Sufficient requirements for the gyrator’s CM stability, that easily can be considered during the design process of common-mode feedback (CMFB) amplifiers, are defined. Based on these stability requirements, a design methodology and a design procedure are proposed. Finally, in order to validate the proposed procedure, a resonator with 20 MHz resonance frequency and a quality factor of 20 is fabricated with UMC 180-nm CMOS technology and its CM stability is examined

A Wide Tuning Range 4th-Order Gm-C Elliptic Filter for Wideband Multi-Standards GNSS Receivers

A 4 th order Gm-C elliptic low-pass filter with a wide continuous tuning range is presented. The continuous tuning is achieved by means of a new tuning circuit which adjusts the bias current of the Gm cell's input stage to control the cut-off frequency. With this tuning circuit, power efficiency is achieved by scaling down the power consumption proportionally to the cut-off frequency while keeping the linearity near constant over a wide range of frequencies. To extend the tuning range of the filter, Gm switching was employed which also acts on the Gm cell's input stage without adding any switches in the signal path. The filter was fabricated using UMC 180-nm CMOS technology on an active area of 0.23 mm2. Its cut-off frequency ranges continuously from 7.4 to 27.4 MHz. This wide range of possible tuning makes the filter suitable for modern wideband GNSS signals in zero-IF receivers. The filter consumes 2.1 and 7.5 mA (from 1.8 V) at its lowest and highest cut-off frequencies, respectively, and achieves a high input IP3 of up to −1.3 dBVRMS

Design Methodology for Controlled-Q Resonators in OTA-based Filters

This paper presents a design methodology for high quality factor resonators based on operational transconductance amplifier (OTA) employed in active filters. The quality factor of a resonator, as its main specification, is translated to the requirements of the OTA. Moreover, the effects of the OTA’s finite output resistance and internal poles are investigated. The results provide a useful chart and a simple methodology to design a resonator with a desired quality factor. The design methodology has been validated by fabricating a resonator with 8 MHz resonance frequency and a quality factor of around 10 using UMC 180-nm CMOS technology

A Versatile 1.4-mW 6-bits CMOS ADC for Pulse-Based UWB Communication Systems

An Analog to Digital Converter (ADC) using the low duty-cycle nature of pulse-based Ultra Wide-Band (UWB) communications to reduce its power consumption is proposed. Implemented in CMOS 180 nm technology, it can capture a 5 ns window at 4 GS/s each 100 ns, which corresponds to the acquisition of one UWB pulse at the pulse repetition rate of 10 mega pulses per second (Mpps). By using time-interleaved Redundant Signed Digit (RSD) ADCs, the complete ADC occupies only 0.15 mm2 and consumes only 1.4 mW from a 1.8 V power supply. The ADC can be operated in two modes using the same core circuits (operational transconductance amplifier, comparators, etc.). The first mode is the standard RSD doubling mode, while the second mode allows improving the signal-to-noise ratio by adding coherently the transmitted pulses of one symbol. For example, for audio applications, a 300 kbps data rate and processing gain up to 15 dB can be achieved at a clock frequency of 10 MHz

Development of a versatile low-power 24 GHz phased array front-end in 90 nm CMOS technology

This paper deals with the development of a four-channel low-power Phased Array Front-End (PhA-FE) at 24 GHz, targeting both low-power radar sensors and battery powered transceiver applications. Typically, PhA-FEs are power hungry architectures due to multiple parallel RF channels in the FE and complex algorithms for beam steering or high bit-rate demodulation in the digital part. In contrast, we target in this paper applications where both beam steering algorithms and data demodulation are relatively simple and hence achievable with low-power digital signal processing. More specifically, we report on four significant building blocks of the architecture, a Low Noise Amplifier (LNA), a Vector Modulator Phase Shifter (VMPS), a Quadrature Voltage Controlled Oscillator (QVCO) and an Analogue to Digital Converter (ADC) that have been designed the first three in 90nm and the last in 180nm CMOS technology. The LNA shows 24.4 dB gain, 3.4 dB NF and −24.4 dBm input P1dB. The single quadrant VMPS has more than 90° of phase control range and shows less than 0.7 dB of gain variation over phase shifting. The QVCO which consumes less than 32mW, buffer included, has a tuning range of 8%. The 6bit 20 MS/s ADC consumes 1.8mW

Path-loss and car-body-effect characterization for smart tires communications at UWB and ISM bands

Next generation of smart tires will improve the safety and stability of the vehicle by monitoring road parameters, such as pavement and rolling conditions, with sensors placed on tire surface. Between the tread and the metal belt of the tire there are only few millimeters of rubber, therefore high miniaturization is necessary to withstand at the extremely high accelerations and to fit in this very limited room. Such kind of miniaturization poses huge limitations on antenna efficiency and available power likely provided by energy scavengers. Therefore, the optimization of the wireless power budget is crucial and it passes through the study of the communication channel. This paper presents a characterization setup that measures the path-loss from the tire surface to the inside of the car where the standard RF receivers, such as RKE at 434 MHz and Bluetooth at 2.4 GHz, are usually located. A calibration procedure has been employed in order to de-embed car-body-effects from the overall path-loss. Moreover, a 4.1 GHz UWB radio has also been considered in this study motivated by the extremely low-power consumption reached by UWB transmitters. The measurement results reflect a complex propagation environment where the car body attenuation plays a marginal role. Instead, the antenna pattern and the reflections from the environment cause the largest attenuation. Moreover, the observed link budget margin is larger and more suitable for implementation within the ISM bands than for the UWB band

The unfinished agenda of communicable diseases among children and adolescents before the COVID-19 pandemic, 1990-2019: a systematic analysis of the Global Burden of Disease Study 2019

BACKGROUND: Communicable disease control has long been a focus of global health policy. There have been substantial reductions in the burden and mortality of communicable diseases among children younger than 5 years, but we know less about this burden in older children and adolescents, and it is unclear whether current programmes and policies remain aligned with targets for intervention. This knowledge is especially important for policy and programmes in the context of the COVID-19 pandemic. We aimed to use the Global Burden of Disease (GBD) Study 2019 to systematically characterise the burden of communicable diseases across childhood and adolescence. METHODS: In this systematic analysis of the GBD study from 1990 to 2019, all communicable diseases and their manifestations as modelled within GBD 2019 were included, categorised as 16 subgroups of common diseases or presentations. Data were reported for absolute count, prevalence, and incidence across measures of cause-specific mortality (deaths and years of life lost), disability (years lived with disability [YLDs]), and disease burden (disability-adjusted life-years [DALYs]) for children and adolescents aged 0-24 years. Data were reported across the Socio-demographic Index (SDI) and across time (1990-2019), and for 204 countries and territories. For HIV, we reported the mortality-to-incidence ratio (MIR) as a measure of health system performance. FINDINGS: In 2019, there were 3·0 million deaths and 30·0 million years of healthy life lost to disability (as measured by YLDs), corresponding to 288·4 million DALYs from communicable diseases among children and adolescents globally (57·3% of total communicable disease burden across all ages). Over time, there has been a shift in communicable disease burden from young children to older children and adolescents (largely driven by the considerable reductions in children younger than 5 years and slower progress elsewhere), although children younger than 5 years still accounted for most of the communicable disease burden in 2019. Disease burden and mortality were predominantly in low-SDI settings, with high and high-middle SDI settings also having an appreciable burden of communicable disease morbidity (4·0 million YLDs in 2019 alone). Three cause groups (enteric infections, lower-respiratory-tract infections, and malaria) accounted for 59·8% of the global communicable disease burden in children and adolescents, with tuberculosis and HIV both emerging as important causes during adolescence. HIV was the only cause for which disease burden increased over time, particularly in children and adolescents older than 5 years, and especially in females. Excess MIRs for HIV were observed for males aged 15-19 years in low-SDI settings. INTERPRETATION: Our analysis supports continued policy focus on enteric infections and lower-respiratory-tract infections, with orientation to children younger than 5 years in settings of low socioeconomic development. However, efforts should also be targeted to other conditions, particularly HIV, given its increased burden in older children and adolescents. Older children and adolescents also experience a large burden of communicable disease, further highlighting the need for efforts to extend beyond the first 5 years of life. Our analysis also identified substantial morbidity caused by communicable diseases affecting child and adolescent health across the world. FUNDING: The Australian National Health and Medical Research Council Centre for Research Excellence for Driving Investment in Global Adolescent Health and the Bill & Melinda Gates Foundation

Global, regional, and national burden of colorectal cancer and its risk factors, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Funding: F Carvalho and E Fernandes acknowledge support from Fundação para a Ciência e a Tecnologia, I.P. (FCT), in the scope of the project UIDP/04378/2020 and UIDB/04378/2020 of the Research Unit on Applied Molecular Biosciences UCIBIO and the project LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy i4HB; FCT/MCTES through the project UIDB/50006/2020. J Conde acknowledges the European Research Council Starting Grant (ERC-StG-2019-848325). V M Costa acknowledges the grant SFRH/BHD/110001/2015, received by Portuguese national funds through Fundação para a Ciência e Tecnologia (FCT), IP, under the Norma Transitória DL57/2016/CP1334/CT0006.proofepub_ahead_of_prin