High linear voltage references circuitry are designed and implemented in TSMC 0.18µm CMOS technology. Previous research has proposed the use of MOS transistors operating in the weak inversion region to replace the bipolar devices in conventional PTAT(proportional to absolute temperature) circuits. However such solutions often have linearity problem in high temperature region due to the current leaking devices in modern deep sub micron and nano-scale CMOS technology. The proposed circuit utilized temperature complementation technique on two voltage references, PTAT and IOAT (independent of absolute temperature) references, to enhance the linearity and produce a more stable IOAT voltage reference. Base on the simulation results, the R-squares of both circuitries are better than 0.999 in a considerable wider temperature range from - 55°C to 170°C. Thus, a fully integrated temperature sensor with wider temperature range is designed and easily to integrate to modern system-on-chip designs with minimal efforts....

System level design of battery operated sensor networks needs high level battery models. As these sensors may operate on very different temperatures the battery models need to be temperature dependent. The paper presents the steps of creating temperature dependent battery models....

Electronics warming has broad applications in the aerospace industry, where electronics assemblies are subject to lower than recommended temperature environments. Prior to operation it is necessary to raise the temperature of the electronics to the minimum safe operating level, recommended by the manufacturer. This is managed by adding an electrical heater inside the electronics assembly enclosure. A very important characteristic of the heater is how quickly the desired temperature needs to be reached. Of course, this characteristic determines the size of the heater needed for the warm up process. Since relatively low failure mode temperatures are often required by the aerospace industry, there is an additional level of complexity involved in designing the optimum size of a heater. In a failure mode condition, the analysis requires a heater to be sized to produce a small amount of heat even under hot environmental conditions. The two requirements of fast warm up time and low failure mode temperatures seem contradictory. The art of the Thermal Management in this type of design is to come up with a specific optimum heater size that can satisfy a rapid warm up requirement and yet not exceed the maximum allowable temperature during a failure mode scenario. Often a thermal engineer needs to work with an electrical engineer to manipulate the control algorithm for the heater in order to satisfy these two requirements. This study will investigate how to approach such a problem and how one can size such heater. Also, optimization techniques are considered in order to choose the proper design among all available solutions. There are two different ways to achieve a desired warm up time of a cold soaked electronics assembly. The first approach may require some manipulation of the location of the heater inside the box or the addition of insulating materials. This approach captures the heat generated by the heater inside the enclosure in order to achieve quicker warm up period. However, the presence of an insulator increases the risk of dangerously high temperatures during a failure mode scenario. To alleviate the insulator effect, the external enclosure heat dissipation mechanism must be altered. This kind of modification is costly and requires additional design steps. This is where the benefit of the second approach comes in. Namely, the desired result of a fast warm up time and lower failure mode temperatures can be achieved by manipulating the heater controller and controlling the amount of power to the heater. A Pulse Width Modulation (PWM) Controller can be used to control not only the amount of heat generated by a heater, but also the percentage of heater "on” time within one pulse width and therefore the warm up time. Having the ability to control the frequency of releasing heat into the cold enclosure allows us to indicate two new parameters : the amount of heat load and the heat load frequency of inserting heat. A thermal management scheme can be developed to optimize the most efficient pair of values that will meet warm up time and failure mode temperature criteria. An analytical model is developed to study the thermal management of such a problem. The analytical model is used to perform an optimization study and to recommend a heater controller design for a given required specification....

This article deals with the creation of a compact thermal model. In this aim, we apply some well-known methods such as FEM model reduction and identification of RC networks. To go further than already existing approaches, we also introduce the use of artificial neural networks (ANNs) to cope with nonlinearities which may appear in thermal phenomenons. A new hybrid model, trying to gather the advantages of ANNs and RC networks, is applied on a simple thermal problem. The need of samples will also lead us to carry out, in parallel, the FEM model reduction. The reduced FEM model will then be used to generate the required databases and validate the compact model results....

Using the finite volume CFD software FLUENT, one fan was studied at a given flow rate (1.5m3/min) for three different operational rotating speeds : 2,000, 2,350 and 2,700 rpm. The turbulent air flow analysis predicts the acoustic behavior of the fan. The best fan operating window, i.e. the one giving the best ratio between noise emissions and cooling performance, can then be determined. The broadband noise acoustic model is used. As the computation is steady state, a simple Multiple Reference Frame model (MRF, also known as stationary rotor approach) is used to represent the fan. This approach is able to capture the effects of the flow non-uniformity at the fan inlet together with their impact on the fan performance. Furthermore, it is not requiring a fan curve as an input to the model. When compared to the available catalog data the simulation results show promising qualitative agreement that may be used for fan design and selection purposes....