Hans W. Pflug

A meter-range UWB transceiver chipset for around-the-head audio streaming

Any around-the-body wireless system faces challenging requirements. This is especially true in the case of audio streaming around the head e.g. for wireless audio headsets or hearing-aid devices. The behind-the-ear device typically serves multiple radio links e.g. ear-to-ear, ear-to-pocket (a phone or MP3 player) or even a link between the ear and a remote base station such as a TV. Good audio quality is a prerequisite and mW-range power consumption is compulsory in view of battery size. However, the GHz communication channel typically shows a significant attenuation; for an ear-to-ear link, the attenuation due to the narrowband fade dominates and is in the order of 55 to 65dB [1]. The typically small antennas, close to the human body, add another 10 to 15dB of losses. For the ear-to-pocket and the ear-to-remote link, the losses due to body proximity and antenna size reduce, however the distance increases resulting in a similar link budget requirement of 80dB.

A high-band IR-UWB chipset for real-time duty-cycled communication and localization systems

A 90nm, IR UWB, duty-cycled transceiver chipset, for operation from 7 to 9.8GHz and compliant to the IEEE802.15.4a and the upcoming IEEE802.15.6 standard, is presented. The complete, duty-cycled transmitter provides +1dBm peak output power, consuming 4.4mW. The receiver front-end shows −88dBm sensitivity at 0.85Mbps and a digital synchronization algorithm enables real-time duty cycling, resulting in a mean power consumption of 3mW.

Human++: wireless autonomous sensor technology for body area networks

Recent advances in ultra-low-power circuits and energy harvesters are making self-powered body wireless autonomous transducer solutions (WATS) a reality. Power optimization at the system and application level is crucial in achieving ultra-low-power consumption for the entire system. This paper deals with innovative WATS modeling techniques, and illustrates their impact on the case of autonomous wireless ElectroCardioGram monitoring. The results show the effectiveness of our power optimization approach for improving the WATS autonomy.

UWB Pulse Shaping for IEEE 802.15.4a

This paper presents a calculation method to analyze ultra-wide band pulse shapes used for wireless communication using the IEEE 802.15.4a standard. The presented equations provide a simple way for designing a standard compliant pulse shape generated with low power consuming circuitry. The main conclusion is that an average power measurement will obtain the same value for all presented pulse shape variations.

Method to Estimate Impulse-Radio Ultra-Wideband Peak Power

This paper provides a method for estimating peak power for impulse-radio ultra-wideband signals. By analyzing the required measurement procedure, a set of equations is derived, which are verified with simulated and measured results. The IEEE 802.15.4a standard is used as an example. The idiosyncracy of IEEE 802.15.4a is the usage of bursts of pulses. Hence, we in this paper propose a method to correctly analyze it. The deviation from the established calculation is shown together with the advantages of using this new method, which is valid for both frequency- and time-domain analysis. The latter turns out to be the preferred way of working. Using the proposed method enables usage of up to 16-24 dB more pulse amplitude, depending on the equipment available and burst width used.

Low power IEEE 802.15.4a UWB digital Rx baseband architecture

This paper presents a low power ultra-wide band digital receiver baseband architecture for handling IEEE 802.15.4a packets in real-time. Real-time processing allows duty cycling of the analog frontend, which is key to achieve low power consumption. The architecture consists of a programmable application specific instruction set processor and a set of application specific integrated circuits. The design is split up into multiple clock domains to meet timing requirements of up to 499.2MHz. The architecture runs in real-time on FPGA, and is synthesizable for 90nm CMOS at 0.84V. This results in a low power flexible C programmable baseband architecture, which is ideal for algorithm development and tuning.

RF and Base-Band circuit blocks for LR-UWB receivers

Low Data Rate Ultra-Wideband (LR-UWB) systems have an enormous potential and compare favorably to other communication systems, in terms of capacity and low-complexity. This stems from the channels located at rather high frequencies (3.5 GHz-10 GHz), which offer each a large signal bandwidth (500MHz). However, these aggressive broadband frequency properties of UWB systems make the design of low-power receivers quite challenging. In this paper the circuit blocks that constitute an LR-UWB receiver are illustrated. They are designed in CMOS 90nm technology. The RF section, including LNAs and oscillators is considered first. Secondly, the problems and the circuit solutions related to the base-band section, including filters and programmable gain amplifiers are addressed.

Practical applications of radiative wireless power transfer

For practical use of radiative wireless power transfer (WPT), it is necessary to design a system which is able to supply circuits with a dynamic loading characteristic. In this paper we present a practical way to obtain efficiency and dc output power characteristics of a WPT system. An Avago HSMS-2852 Schottky diode pair is used to rectify the RF power. The diode pair is matched to a 50 Ω input impedance and loaded with an Texas Instruments TI BQ22570 Power Management Circuit. The system is able to deliver 20 mW dc output power during 10 ms with a period of 8.7 s at an RF input power level of -10 dBm. This corresponds to a distance in excess of 9 m having a 6 dBi receiving antenna and using a 3 W EIRP transmitter at 868 MHz.

Radio channel characterization for 400 MHz implanted devices

The wireless communication channel around/in the human body is a difficult propagation environment. This paper presents measurement and simulation results to characterize such a channel. A fluid human body model is employed to emulate the inside of a human body. The paper details the fluid human model and path loss model parameters at 400 MHz (MICS band). It is shown that the simulated and measured results are in a close agreement, for instance at a distance of 20 cm and a implant depth of 10 cm, the measurement results in a path loss of -42.1 dB and the simulation in -43.0 dB. The effect of human model shape on measured path loss is analyzed. Furthermore, simulations are employed to characterize this effect. Using the path loss model a top-level link budget is evaluated to determine the feasibility of a given implant device compliant to IEEE802.15.6-WBAN-400 MHz standard.

UWB pulse amplitude estimation method for IEEE 802.15.4a

This paper presents a novel mathematical model to relate pulse amplitude of impulse radio UWB signals to peak power as limited by regulatory bodies. In contrast to existing methods, this model explicitly takes bursts of pulses into account, as is the case for the signaling scheme in the IEEE 802.15.4a standard. Based on insights obtained using this novel model, it enables the usage of up to 16 to 24 dB higher pulse amplitude for all peak-power limited IR systems, as is the case for a majority of the data rate modes in the IEEE 802.15.4a standard.