A new technique to measure a capacitor or a capacitive sensor by means of a direct sensor-to-microcontroller interface circuit that does not need a calibration capacitor is proposed. Basically, the measurement process consists of three consecutive steps of charge, discharge and charge of the capacitor under test. A non-linear equation is obtained and solved that is dependent only on known circuit parameters. Experimental results show that it is possible to measure a wide range of capacitor values with a maximum deviation of 2% from the reference value, and that temperature changes from 18 to 70°C yield relative errors below 0.1%. For the lowest measured capacitor range (33 pF-4.7 nF) the uncertainty holds below 1 pF which enables measurement of commercially available capacitive sensors. The main advantage of the proposed technique is cost and space reduction of the final design.
Gorreta, S.; Barajas, E.; Kowalski, L.; Atienza, M.T.; Dominguez, M.; Jimenez, V. Electronics Letters Vol. 51, num. 19, p. 1499-1500 DOI: 10.1049/el.2015.1947 Data de publicació: 2015-09-17 Article en revista
A new circuit is described which applies a configurable voltage across an RTD while the current flowing through it is measured with a current mirror. The circuit also allows working with voltages above the IC supply voltage to cope with the high power RTD dissipation normally required in thermal anemometers. The circuit is periodically calibrated to cancel the errors and amplifier offset and therefore improves measurement accuracy. Experimental measurements of the circuit fabricated using 0.35 mu m AMS technology show the functionality and improved power efficiency.
A first reported complementary metal-oxide semiconductor (CMOS)-integrated acceleration sensor obtained through isotropic inter-metal dielectric (IMD) etching of a back-end-of-line (BEOL) integrated circuit interconnection stack, without any additional substrate etching steps, is presented. The mechanical device composed of a CMOS-process 8 mu m-thick metal-via-metal stack of 135 mu m diameter and suspended 2.5 mu m over a bottom fixed electrode, has a resonance frequency of 20 kHz, a sensing capacitance of 50 fF with sensitivity 14 aF/G and it is integrated on the same substrate with a simple low-noise amplifier reaching 25 mG of RMS noise measured from 0.25 to 100 Hz bandwidth.
Test structures are key elements to characterise and identify the main contributors to yield loss in wiring structures. Among such monitors, comb-meander-comb structures have been widely used owing to their simplicity and reduced number of pads. With continuous scaling of dimensions and use of copper in interconnections, open defects has arisen as the most common defect affecting the interconnection, focusing thus on an important part of the research effort. In fact, present electrical methodologies are able to detect, localise and predict the resistance of weak (resistive) opens. However, such methodologies are not able to locate full opens. This lack of information may be useful for faster ramp-up and yield improvement, among others. In this context, a simple electrical methodology to predict the location of full opens in comb-meander-comb structures is presented. Experimental measurements carried out in a 65 nm technology die corroborate the feasibility of the approach.
Today, the vast majority of personal communication devices, such as laptops, smartphones, and logically wireless fidelity (Wi-Fi) access points feature IEEE 802.11 chipsets. In turn, wake-up radio (WuR) systems are used to reduce the significant energy waste that wireless devices cause during their idle communication mode. A novel WuR system is introduced that enables any IEEE 802.11-enabled device to be used as a WuR transmitter without requiring any hardware modification. The corresponding developed WuR receiver achieves a remarkably low power consumption of 10.8 µW and operates in the Wi-Fi 2.4 GHz band. By means of thorough physical tests, it is shown that the proposed IEEE 802.11-based WuR system enables important energy savings.
In coplanar waveguide (CPW) circuits, printed balanced antennas must be excited through baluns. These baluns often feature coplanar-to-slotline transitions that must be tuned and matched by electromagnetic optimisation, and may interfere with the antenna backward radiation. A new CPW balun for printed balanced antennas is presented and modelled. As its multimodal circuit model makes clear, it integrates an impedance-matching network within its structure that can be analytically designed. The balun has been experimentally tested, exhibiting good agreement with its circuit model and a weak electromagnetic interaction with the antenna radiation.
Directly interfacing sensors that link sensors to micro-controllers without a signal conditioning circuit or an analogue-to-digital converter on the one side and energy harvesting systems on the other side are two key enabling technologies to create self-powered autonomous low-cost and low-maintenance sensor networks. In this reported work, both technologies are concurrently combined in such a way that the duty cycle of the pulsed power supply provided by the harvesting system itself yields in turn a temperature gradient sensor functionality. Originally conceived to power a low-power satellite beacon in a CubeSat project, it has found application, among other applications, in automatic air conditioning and heating systems aiming smart buildings.
A new design based on the flipped-structure for RF active inductors is presented. The conventional flipped-active inductor (FAI) composed of only two transistors is considered as a starting structure. However, it suffers from low-voltage swing, which increases the nonlinearity. Additionally, it requires high power consumption to achieve adequate inductance and quality factor values. A circuit topology named cascoded FAI (CASFAI) based on the basic FAI is proposed. A common-gate transistor added in the feedback path of the proposed CASFAI results in an increase of the voltage swing and linearity as well as the feedback gain. The performance metrics of such active inductors are benchmarked by analytical models and validated in the ADS using a 0.18 µm CMOS process. The results indicate that the CASFAI can achieve a notably higher quality factor and higher inductance values while consuming less power in comparison to the basic FAI.
A yield formulation model to estimate the amount of lithography distortion expected in a printed layout is proposed. The yield formulation relates the probability of non-failure of a lithography hotspot with the
yield loss. The application of the yield model is demonstrated for three different layout configurations showing that unidimensional designs may improve manufacturing yield.
Contreras, A.; Ribó, M.; Pradell, L.; Casals-Terré, J.; Giacomozzi, F.; Iannacci, J. Electronics Letters Vol. 49, num. 11, p. 704-706 DOI: 10.1049/el.2013.0681 Data de publicació: 2013-05-23 Article en revista
A K-band RF-MEMS uniplanar second-order bandpass filter with
reconfigurable bandwidth is presented. The filter is based on inductively-coupled
half-wavelength slotline resonators and CPW-slotline
multimodal immittance inverters (MIIs). The coupling inductance
and the MII length are reconfigured using RF-MEMS ohmic-contact
switches. Experimental results show a 3 dB relative-bandwidth
change from 4.5 to 8.5% (maintaining a Butterworth response), and
insertion losses of 5.2 and 3.7 dB for either state.
Proposed is a new carrier phase synchronisation scheme used to provide a stable phase reference to a very distant station. Channel induced phase fluctuations are characterised and compensated for with a round-trip loop in which three different frequency tones are simultaneously used. The bandwidth required to allocate this set of tones is independent of carrier frequency.
Proposed is a new carrier phase synchronisation scheme used to
provide a stable phase reference to a very distant station. Channel
induced phase fluctuations are characterised and compensated for
with a round-trip loop in which three different frequency tones are simultaneously
used. The bandwidth required to allocate this set of tones is
independent of carrier frequency.
The energy consumption of modern communications systems is
dominated by the signal processing and shaping circuitry. Assuming
a rate-independent processing power consumption, the energy per bit
spent for signal processing can be effectively reduced by increasing
the transmission power. The optimal relation between processing and
transmission power for energy efficient communications is derived.
This relation is called processing-to-amplifier power ratio (PrAPR).
A novel handset antenna consisting of two small antennas is proposed to mitigate finger loading effects. Both antennas are excited with a different phase in order to maximise the bandwidth. A phantom hand has been used to perform the experiments. It demonstrates how the finger affects the radiation behaviour for three particular positions of the finger over the antenna area. Experimental results feature a wider input impedance bandwidth and a higher degree of immunity to finger loading effects when compared with a single-element approach.
This paper presents the analysis of inter-operator agreements to exchange radio resources in a multi-operator scenario, to improve radio resource usage and operator revenue. The establishment of these agreements increases user perception of the service and reduces churning rate.
Rodriguez-Montanes, R.; Arumi, D.; Figueras, J.; Eichenberger, S.; Hora, C.; Kruseman, B. Electronics Letters Vol. 43, num. 21, p. 1140-1141 DOI: 10.1049/el:20072117 Data de publicació: 2007-10 Article en revista
Interconnecting lines with full open defects become floating lines. In nanometric CMOS technologies, gate tunnelling leakage currents impact the behaviour of these lines, which cannot be considered electrically isolated anymore. The voltage of the floating node is determined by its neighbours and leakage currents. After some time an equilibrium is reached between these effects. Theoretical analysis and experimental evidence of this behaviour are presented.
Electronics Letter of the Month
Interconnecting lines with full open defects become floating lines. In nanometric CMOS technologies, gate tunnelling leakage currents impact the behaviour of these lines, which cannot be considered
electrically isolated anymore. The voltage of the floating node is determined by its neighbours and leakage currents. After some time an equilibrium is reached between these effects. Theoretical analysis and experimental evidence of this behaviour are presented.
Bridging defects generate two currents related to the fault-free case: bridge current and downstream current. The latter may complicate the diagnosis of bridging defects. However, in CMOS technologies, the downstream current can be minimised at low power supply (VDD) values, thus facilitating the diagnosis of such defects. Experimental evidence of this behaviour is presented
The dynamic range and error performance of the diode power detector
used to denormalise the digital correlations in interferometric radiometers
is analysed by means of a second-order model of the diode
response. This gives an easy method to establish system dynamic
range as a trade-off between both the error contribution of measurement
uncertainty and diode nonlinearity. The method is illustrated by
analysing the power measurement system of the MIRAS-SMOS
W-CDMA performance is tightly coupled to the amount of interference in the air interface and eventually depends on many strongly interrelated system parameters that need to be suitably managed through radio resource management (RRM) strategies in order to achieve a high efficiency. Interference characterisation in terms of average and standard deviation, which are suitable for radio network planning, may not suffice for a proper RRM design because of its inherently dynamic nature. The time correlation of the interference and the main system level parameters affecting its dynamics are raised: shadow fading, mobile speed, traffic characteristics and cell load.
The presence of different service classes in the context of 3G mobile communication systems opens up new possibilities to exploit the spectrum in an efficient way. In the search of such a high efficiency, radio network congestion may arise and it is mandatory to include suitable algorithms to deal with these situations. Here, congestion control mechanisms in the radio interface of UTRA FDD are proposed and analysed. Results show that under congestion it seems more suitable to adopt firm and strict rate control decisions rather than softer policies.
The focus of this report is synthetic aperturc radar (SAR) interferoinctric
techniques for mapping applications, in the presencc of
possible high squint values. Theoretical and expcrimental analysis
show the presence of limitations that are overcome by the proposcd