A long-range UHF RF identification (RFID) sensor has been designed using a 0.35-µm CMOS standard process. The power-optimized tag, combined with the ultralow-power temperature sensor, allows an ID and a temperature reading range of 2 m from a 2-W effective radiated power output power reader. The temperature sensor is based on a ring oscillator, where the temperature dependence of the oscillation frequency is used for thermal sensing. The temperature sensor exhibits a resolution of 0.035 • C and an inaccuracy value lower than 0.1 • C in the range from 35 • C to 45 • C after two-point calibration. The average power consumption of the temperature sensor is only 110 nW at ten conversions per second while keeping a high resolution and accuracy. These properties allow the use of the RFID as a batteryless sensor in a wireless human body temperature monitoring system. Index Terms-CMOS analog front end, digital core, high accuracy, low power, RF identification (RFID), temperature sensor, ultrahigh frequency (UHF).

Articles you may be interested inNoise and terahertz rectification linked by geometry in planar asymmetric nanodiodes Appl. Phys. Lett. 94, 093512 (2009); 10.1063/1.3095845Terahertz Gunn-like oscillations in InGaAs/InAlAs planar diodes

Shot-noise suppression is investigated in nondegenerate diffusive conductors by means of an ensemble Monte Carlo simulator. The universal 1͞3 suppression value is obtained when transport occurs under elastic collision regime provided the following conditions are satisfied: (i) The applied voltage is much larger than the thermal value; (ii) the length of the device is much greater than both the elastic mean free path and the Debye length. By fully suppressing carrier-number fluctuations, long-range Coulomb interaction is essential to obtain the 1͞3 value in the low-frequency limit.[ S0031-9007(98)05732-9] PACS numbers: 72.70. + m, 73.23.Ad, 73.50.Td In recent years kinetic phenomena in mesoscopic structures are offering a fascinating scenario for fundamental research [1]. One of the most up-to-date subjects is shotnoise suppression in disordered conductors. Here, the excess noise power has been predicted to comprise exactly one-third of the full shot-noise value S I 2eI. This result has been credited to different theoretical approaches as applied to several microscopic models of disordered conductors. For a phase-coherent model Beenakker and Büttiker [2] obtained the result using a bimodal distribution of transmission eigenvalues with the help of random matrix theory to calculate averages. For a semiclassical 1D model which includes Pauli principle Nagaev [3] found the same result using a Boltzmann kinetic approach within an elastic and energy independent relaxation-time approximation. For a semiclassical sequential tunneling model de Jong and Beenakker [4] obtained the 1͞3 value within a Boltzmann-Langevin approach in the limit of an infinite number of equal barriers and independently from the value of their transmission coefficient. Compatible results have been found by Liu et al.[5] from a semiclassical implementation of a Monte Carlo simulation which includes Pauli principle. For a phase-coherent model Nazarov [6] has proven the universality of this result in the diffusive limit for arbitrary shape and resistivity distribution of the conductor as long as its length is greater than the carrier mean free path. Experimental evidence of the reduced shot-noise level close to the predicted 1͞3 value in diffusive mesoscopic conductors has been provided in [7][8][9].From the above it is argued that the 1͞3 value of the suppression factor g S I ͞2eI is a universal phenomenon whose physical meaning should lay beyond classical or quantum mechanics and originate from some unifying concept. The aim of this Letter is to address this issue. We conjecture that discreteness of charge transport is at the basis of such a concept, and that a transport dominated by elastic interactions is ultimately the physical reason for the 1͞3 suppression independently from the quantum or classical approach used. Both the (apparently unrelated) coherent [2] and semiclassical [3] contexts where the reduction factor 1͞3 has appeared assume a degenerate Fermi gas, and the noise reduction comes from the regulation of electron motion by the ...

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