Arjan Breeschoten

A 2.4 GHz ULP OOK Single-Chip Transceiver for Healthcare Applications

This paper describes an ultra-low power (ULP) single chip transceiver for wireless body area network (WBAN) applications. It supports on-off keying (OOK) modulation, and it operates in the 2.36-2.4 GHz medical BAN and 2.4-2.485 GHz ISM bands. It is implemented in 90 nm CMOS technology. The direct modulated transmitter transmits OOK signal with 0 dBm peak power, and it consumes 2.59 mW with 50% OOK. The transmitter front-end supports up to 10 Mbps. The transmitter digital baseband enables digital pulse-shaping to improve spectrum efficiency. The super-regenerative receiver front-end supports up to 5 Mbps with -75 dBm sensitivity. Including the digital part, the receiver consumes 715 μW at 1 Mbps data rate, oversampled at 3 MHz. At the system level the transceiver achieves PER=10 -2 at 25 meters line of site with 62.5 kbps data rate and 288 bits packet size. The transceiver is integrated in an electrocardiogram (ECG) necklace to monitor the hearts electrical property.

A voltage-scalable biomedical signal processor running ECG using 13pJ/cycle at 1MHz and 0.4V

Recent work on designing ultra-low-power systems has focused on the sub-threshold regime [1–3] and an energy efficiency of a few pJ/cycle was reported. While operating at the minimum energy point is attractive for energy-frugal devices like those used for wireless biomedical signal monitoring, the achieved clock frequency is usually in the kHz range. The low frequency combined with limited processing capacity, small on-chip memory, and low computation precision prevents the use of these systems for complex ambulatory monitoring beyond a simple ECG algorithm. Low-voltage systems with more computational power are demonstrated in [4] and [5].

A 345 µW Multi-Sensor Biomedical SoC With Bio-Impedance, 3-Channel ECG, Motion Artifact Reduction, and Integrated DSP

This paper presents a MUlti-SEnsor biomedical IC (MUSEIC). It features a high-performance, low-power analog front-end (AFE) and fully integrated DSP. The AFE has three biopotential readouts, one bio-impedance readout, and support for general-purpose analog sensors The biopotential readout channels can handle large differential electrode offsets ( ±400 mV), achieve high input impedance ( >500 M Ω), low noise ( 620 nVrms in 150 Hz), and large CMRR ( >110 dB) without relying on trimming while consuming only 31 μW/channel. In addition, fully integrated real-time motion artifact reduction, based on simultaneous electrode-tissue impedance measurement, with feedback to the analog domain is supported. The bio-impedance readout with pseudo-sine current generator achieves a resolution of 9.8 m Ω/ √Hz while consuming just 58 μW/channel. The DSP has a general purpose ARM Cortex M0 processor and an HW accelerator optimized for energy-efficient execution of various biomedical signal processing algorithms achieving 10 × or more energy savings in vector multiply-accumulate executions.

A 2.4GHz ULP OOK single-chip transceiver for healthcare applications

Wireless body-area networks (WBAN) are used for communication among sensor nodes operating on, in or around the human body, e.g. for healthcare purposes. In view of energy autonomy, the total energy consumption of the sensor nodes should be minimized. Because of their low complexity, a combination of the super-regenerative (SR) principle [1–3] and OOK modulation enables ultra-low power (ULP) consumption. This work presents a 2.4GHz ULP OOK singlechip transceiver for WBAN applications. A block diagram of the implemented transceiver is shown in Fig. 26.3.1. Next to the direct modulation TX [4] and SR RF [5] front-ends, this work integrates analog and digital baseband, PLL functionality and additional programmability for flexible data rates, and achieves ultra-low power consumption for the overall system.

An Ultra Low Energy Biomedical Signal Processing System Operating at Near-Threshold

This paper presents a voltage-scalable digital signal processing system designed for the use in a wireless sensor node (WSN) for ambulatory monitoring of biomedical signals. To fulfill the requirements of ambulatory monitoring, power consumption, which directly translates to the WSN battery lifetime and size, must be kept as low as possible. The proposed processing platform is an event-driven system with resources to run applications with different degrees of complexity in an energy-aware way. The architecture uses effective system partitioning to enable duty cycling, single instruction multiple data (SIMD) instructions, power gating, voltage scaling, multiple clock domains, multiple voltage domains, and extensive clock gating. It provides an alternative processing platform where the power and performance can be scaled to adapt to the application need. A case study on a continuous wavelet transform (CWT)-based heart-beat detection shows that the platform not only preserves the sensitivity and positive predictivity of the algorithm but also achieves the lowest energy/sample for ElectroCardioGram (ECG) heart-beat detection publicly reported today.

Improving energy-efficiency in building automation with event-driven radio

Sensor, actuator, and radio constitute the three basic components in a building automation system. Among all the three, radio consumes a significant part of the total power. In this paper, an ultra-low power event-driven radio is proposed as a solution to minimize the power consumption of a building automation system. Generic system architecture is formalized according to the application scenario. Event-driven radio is compared against other commercial low power radios. Our analysis shows that significant energy efficiency enhancement is achieved by an event-driven radio. Based on the state of the art micro power technology, possibility of implementing autonomous radio is also investigated in the building automation scenario.

Ultra Low-Power Wireless Body-Area Sensor Networks

In wireless body area network (WBAN) applications, wireless sensors are used to collect, monitor and transmit vital signs and other medical information. In such scenarios, it is critical to maximize the autonomy, while satisfying application performance. A unique platform for introduction of such ultra-low power technology components is an electrocardiography (ECG) patch for BAN applications, and is taken in this work as an example to illustrate the development of an ultra low-power transceiver.

Real time non-coherent synchronization method in 6–10.6 GHz IR-UWB demonstrator chipset

A theoretical model for non-coherent start-of-frame-delimiter (SFD) detection in IEEE 802.15.4a is presented and closed form solutions for SFD threshold and signal-to-noise ratio (SNR) estimation are derived. The derived results are implemented in an impulse radio ultra wide band (IR-UWB) demonstrator operating in the 6-10.6 GHz UWB band. The demonstrator is designed for low power operation (in the mW range for combined digital base band (DBB) & radio frequency (RF)). The transmitter (TX) RF is duty cycled at pulse level and the receiver (RX) RF is switched to pulse level duty cycling when possible. Moreover, digital TX and RX resources are only switched on when needed. Measurement results are in close agreement with the derived closed form solutions.

A 8mW-RX/113mW-TX, Sub-GHz SoC with time-dithered PA ramping for LPWAN applications

This work presents a fully-integrated sub-GHz radio System on Chip (SoC) for Low-Power Wide-Area Networks (LPWAN) and Internet of Things (IoT) applications. The receiver (RX) achieves 77dB blocker rejection and −106dBm sensitivity at 50kbps. The transmitter (TX) features a Switched-Capacitor Power Amplifier (SCPA) that delivers 13.5dBm output power. To fulfil stringent Japanese emission regulation, a novel digitally time-dithered SCPA ramping technique is proposed. The presented RX and TX consume 8mW and 113mW, respectively, from a supply as low as 1.2V.

An energy-aware and scalable UWB Impulse Radio baseband supporting coherent reception

A scalable low power Impulse Radio (IR) receiver baseband has been developed for an around-the-body audio streaming use case, supporting both coherent and non-coherent operation modes. With careful hardware/software co-optimization, the receiver algorithms are implemented using an Application-Specific-Instruction-set-Processor (ASIP) and several optimized hardware accelerators, allowing scalability and support of multi-mode operations in an energy-efficient manner. The receiver baseband is designed in a 90 nm standard CMOS process and is fully verified with the RF frontend. By using an all-digital parallel synchronization module, a short timing acquisition phase is realized, reducing synchronization overhead. In combination with a comprehensive set of low power measures, including hardware/software partitioning, parallelism, module level clock gating, multiple clock domains, operand isolation, multi voltage domains (MVD) and power gating techniques, an average power consumption of 5.6 mW for a 0.85 Mb/sec data rate mode is realized. This corresponds to 10.1pJ/bit for the coherent data processing of an 84 data bytes packet. Furthermore, the design is capable of processing 499.2 MSamples/sec at 840 mV.