Josef Prainsack

A Bulk Acoustic Wave (BAW) Based Transceiver for an In-Tire-Pressure Monitoring Sensor Node

Attaching a tire pressure monitoring system (TPMS) on the inner liner of a tire allows sensing of important additional technical parameters, such as vehicle load or tire wearout. The maximum weight of the sensor is limited to 5 grams including package, power supply, and antenna. Robustness is required against extreme levels of acceleration. The node size is limited to about 1 cm3 to avoid high force-gradients due to device-deformation and finally, a long power supply lifetime must be achieved. In this paper a low-power FSK transceiver is presented. Exploiting BAW resonators the use of a bulky and shock-sensitive crystal and a PLL can be avoided. This makes the system more robust and radically reduces the start-up time to 2 ¿s from few ms as in state-of-the-art crystal oscillator based systems. The current consumption of the transceiver is 6 mA in transmit mode with a transmit output power of 1 dBm and 8 mA in receive mode with a sensitivity of -90 dBm at a data rate of 50 kBit/s and a bit error rate of 10-2. The transceiver ASIC and a microcontroller ASIC, a MEMS sensor, and a BAW die are arranged in a 3-D chip stack for best compactness, lowest volume, and highest robustness. The sensor node allows sensing of pressure, acceleration, supply voltage and temperature.

A robust wireless sensor node for in-tire-pressure monitoring

State-of-the-art tire pressure monitoring systems (TPMS) are wireless sensor nodes mounted on the rim. Attaching the node on the inner liner of a tire allows sensing of additional technical parameters, such as road condition, tire wearout, temperature, tire friction, side slip, wheel speed, and vehicle load. They may be used for improved tracking and engine control, feedback to the power train and car-to-car communication purposes.

A power management unit for ultra-low power wireless sensor networks

Wireless sensor networks become more and more attractive due to their ongoing miniaturization and decreasing costs. One of the major challenges concerning the design is the power consumption of the wireless sensor node. Low power consumption is mandatory to guarantee a long lifetime if a battery is used as a power source or to allow the use of an energy harvester. In this work a multi-stage power management for a wireless sensor node is presented. Energy-efficient power management is achieved by employing several state machines controlling different power domains which can be turned on and off separately depending on the operating mode of the wireless sensor node. A test chip has been produced in an Infineon 130nm CMOS process. The presented wireless sensor node consumes 240 nA in power down mode, most of which is leakage current. In different deep-sleep modes it consumes between 750 nA and 1.5 µA.

Miniaturised Sensor Node for Tire Pressure Monitoring (e-CUBES)

Tire pressure monitoring systems (TPMS) are beneficial for the environment and road and passenger safety. Miniaturizing the TPMS allows sensing of additional parameters. This paper presents a miniaturized TPMS with a volume less than 1 cm3, realised by 3D stacking and through-silicon via (TSV) technology. Suitable technologies with low electrical resistance and high bond strengths were evaluated for stacking the microcontroller, transceiver, pressure sensor and bulk acoustic resonator (BAR) in the TPMS. 60 μm deep W-filled TSVs with resistance 0.45 Ω and SnAg micro bumps with a bond strength of 53 MPa were used for stacking the transceiver to the microcontroller. TSVs through the whole wafer thickness with resistance 6 Ω were used for the pressure sensor. Au stud bumps were used for stacking the pressure sensor and BAR devices. The final TPMS stack was packaged in a moulded interconnect device (MID) package.

A bulk acoustic wave(BAW)-based sensor node for automotive wireless sensor networks

SummaryThe following paper presents a 2.1 GHz transceiver, which makes use of BAW resonators to replace the external quartz crystal and the external band select filter. It has been fabricated in a 130 nm CMOS process and has a power consumption of 5 mA. To derive the specifications for the transceiver the requirements of a TPMS have been taken into consideration.ZusammenfassungDer folgende Artikel stellt einen 2,1-GHz-Transceiver vor, der anstelle einer externen Quarzreferenz und eines externen Hochfrequenzfilters BAW-Resonatoren einsetzt. Der Chip wurde in einem 130-nm-CMOS-Prozess gefertigt und hat einen Stromverbrauch von 5 mA. Um die Spezifikationen abzuleiten, wurden die Anforderungen an ein TPMS (Reifendrucküberwachungssystem) betrachtet.

3D Integration of MEMS and IC: Design, Technology and Simulations

A 3D integrated silicon stack consisting of two MEMS devices and two IC devices is presented. The MEMS devices are a pressure sensor and a bulk acoustic resonator (BAR). The stack was constructed for a tire pressure monitoring system (TPMS) which was one out of three demonstrators for an EU funded project called e-CUBES. Thermal simulations were performed to check the level of thermo-mechanical stresses induced on the pressure sensor membrane during extreme environmental conditions. Additional simulations were made to calculate the exact temperature on the BAR device during operation as this was important for the operational frequency. This paper presents and discusses the technology choices made for the stacking of the pressure sensor and the BAR. Results are given from simulations, initial short-loop experiments and for the final stacking.

Asynchronous logic application in a power management unit for ultra low power wireless sensor nodes

This work presents the application of asynchronous logic style to control circuits of the on-chip power management unit (PMU) in a wireless sensor node. Because of the inherent property of asynchronous logic - to operate without any synchronous clock signal - it is the first choice circuit class for controllers in a clock-less environment. Due to the nature of the asynchronous logic, as it is to work in sensitivity to asynchronous input-changes without being separated by clock edges, the construction of such an asynchronous finite state machine (AFSM) requires careful synthesis and implementation methodology. The asynchronous circuit is realized by means of thick gate oxide transistors and it is directly connected to the power supply. Hence, no voltage regulator and no bandgap are required for the operation of the low power asynchronous circuit. The power management unit itself is applied in the architecture of an ultra low power sensor node circuit. Such circuits are supplied by a limited battery voltage or by an energy harvester and require low power architectures in order to deliver long operating times, especially during the power-down phase of the full circuit. The transceiver is manufactured in a 130 nm CMOS process and has to operate between −40 and 125°C.

Attitudes of social science students in Israel and Austria towards the Belated Twins scenario-an exploratory study

This article discusses results of a questionnaire survey of 156 university students in Israel and Austria examining reactions towards the Belated Twins scenario, which entails the artificial twinning of embryos of which one is immediately carried to term while the other one is born later. The scenario resembles a case of human reproductive cloning in terms of result (the creation of genetically identical individuals in a time-delayed manner) but it involves gamete fusion like “natural” reproduction. By means of qualitative text analysis we discuss the core themes mobilized both in support and opposition to the scenario. While Israeli and Austrian respondents held similar general attitudes (about half were in favour of legalizing Belated Twins, while about a third opposed it), they drew partly on different arguments to arrive at their conclusions. In both groups, uncertainty stemming from “novel” elements in the scenario was regularly interpreted as negatively exacerbating existing issues.

Optimum receiver based on single bit quantization

Nonlinear receiver architectures employing a limiting amplifier for analog-to-digital conversion are often applied in low-power wireless communications to reduce hardware complexity and power consumption. These advantages come at the cost of a degradation in performance compared to their linear counterparts. This work presents the optimum receiver for 1-bit quantized signals and provides the analytical relations for the resulting bit error rates (BER) for binary modulation schemes. The linear coherent matched filter receiver is shown to be optimal for 1-bit quantized receive signals in additive white Gaussian noise (AWGN). Finally the BERs for binary frequency shift keying (BFSK) and binary phase shift keying (BPSK) modulation are analyzed exemplarily and the presented relations are confirmed by numerical simulation.

Performance of a limiting amplifier in white and colored noise

Nonlinear receiver architectures are often employed in low-power wireless communications to reduce hardware complexity and power consumption at the cost of a degradation in performance compared to their linear counterparts. This work presents analytical and statistical methods to quantify this degradation in performance. It is shown that the maximum degradation is equal to −1.96 dB in terms of output signal to noise ratio. If the noise is colored, e.g. due to a preceding channel filter, the performance degradation can be reduced significantly.