N. Van Helleputte

A 160

This paper proposes a 3-channel biopotential monitoring ASIC with simultaneous electrode-tissue impedance measurements which allows real-time estimation of motion artifacts on each channel using an an external μC. The ASIC features a high performance instrumentation amplifier with fully integrated sub-Hz HPF rejecting rail-to-rail electrode-offset voltages. Each readout channel further has a programmable gain amplifier and programmable 4th order low-pass filter. Time-multiplexed 12 b SAR-ADCs are used to convert all the analog data to digital. The ASIC achieves >; 115 dB of CMRR (at 50/60 Hz), a high input impedance of >; 1 GΩ and low noise (1.3 μVrms in 100 Hz). Unlike traditional methods, the ASIC is capable of actual motion artifact suppression in the analog domain before final amplification. The complete ASIC core operates from 1.2 V with 2 V digital IOs and consumes 200 μW when all 3 channels are active.

\mu{\rm A}

This paper presents a fully integrated flexible ultra-low power UWB impulse radio receiver, capable of cm-accurate ranging. Ultra-low-power consumption is achieved by employing the quadrature analog correlating receiver architecture, by exploiting the duty-cycled nature of the system, by operating in the sub-1 GHz band as well as by careful circuit design. Two pulse rates, 39.0625 Mpulses per second (Mpps) and 19.531 Mpps, and a wide range of processing gains (0-18 dB) are supported. Also, the acquisition algorithm and accuracy can be adapted at run time. This flexible implementation allows to dynamically trade power consumption for performance depending on the operating conditions and the application requirements. The receiver prototype was manufactured in 130 nm CMOS and the active circuit area measures 4.52 mm2. The IC contains a complete analog front-end, digital backend and implements the algorithms necessary for acquisition, synchronization, data reception and ranging. Consuming 4.2 mW when operating at 39.0625 Mpps, it achieves an energy efficiency of 108 pJ/pulse. A 1.3 Mb/s wireless link over more than 10 m in an office-like environment has been demonstrated under direct line-of-sight (LOS) conditions with a raw packet-error-rate (PER) less than 10% and cm-accurate ranging.

Biopotential Acquisition IC With Fully Integrated IA and Motion Artifact Suppression

This paper presents an integrated ultra-low power analog front-end (AFE) architecture for UWB impulse radio receivers. The receiver is targeted towards applications like wireless sensor networks typically requiring ultra energy-efficient, low data-rate communication over a relative short range. The proposed receiver implements pulse correlation in the analog domain to severely relax the power consumption of the ADCs and digital backend. Furthermore a fully integrated prototype of the analog front-end, containing a PLL, programmable clocking generator, analog pulse correlator, a linear-in-dB variable gain amplifier and a 4-bit ADC, is demonstrated. Several design decisions and techniques, like correlation with a windowed LO instead of with a matched template, exploiting the duty-cycled nature of the system, operation in the sub-1 GHz band as well as careful circuit design are employed to reach ultra-low power consumption. The analog front-end was manufactured in 130 nm CMOS and the active circuit area measures 1000 mum times 1500 mum. A maximum channel conversion gain of 50 dB can be achieved. Two symbol rates, 39.0625 M pulses per second (Mpps) and 19.531 Mpps are supported. The AFE consumes 2.3 mA from a 1.2 V power supply when operating at 39.0625 Mpps. This corresponds to an energy consumption of 70 pJ/pulse. A wireless link over more than 10 m in an office-like environment has been demonstrated at 19.531 Mpps with a PER < 1E -3 under direct LOS conditions.

A Reconfigurable, 130 nm CMOS 108 pJ/pulse, Fully Integrated IR-UWB Receiver for Communication and Precise Ranging

Ambulatory monitoring of the electrocardiogram (ECG) is a highly relevant topic in personal healthcare. A key technical challenge is overcoming artifacts from motion in order to produce ECG signals capable of being used in clinical diagnosis by a cardiologist. An electrode-tissue impedance is a signal of significant interest in reducing the motion artifact in ECG recordings on the go. A wireless system containing an ultralow-power analog front-end ECG signal acquisition, as well as the electrode-tissue impedance, is used in a validation study on multiple subjects. The goal of this paper is to study the correlation between motion artifacts and skin electrode impedance for a variety of motion types and electrodes. We have found that the correlation of the electrode-tissue impedance with the motion artifact is highly dependent on the electrode design the impedance signal (real, imaginary, absolute impedance), and artifact types (e.g., push or pull electrodes). With the chosen electrodes, we found that the highest correlation was obtained for local electrode artifacts (push, pull, electrode) followed by local skin (stretch, twist, skin) and global artifacts (walk, jog, jump). The results show that the electrode-tissue impedance can correlate with the motion artifacts for local disturbance of the electrodes and that the impedance signals can be used in motion artifact removal techniques such as adaptive filtering.

A 70 pJ/Pulse Analog Front-End in 130 nm CMOS for UWB Impulse Radio Receivers

This paper studies the different power-performance trade-offs at architectural and block level to come to the most energy-efficient UWB system for operation in the 0-960MHz frequency band. This is achieved by designing for the lowest energy per useful received bit. Different receiver architectures are explored and compared against each other. After the selection of the most optimal architecture, the trade-offs inside the different analog building blocks of this receiver are studied. Our results show that the most energy-efficient solution makes use of a complex analog correlation UWB receiver, with an LNA with a Pin,1dBc back-off of -5dB, 3-bit ADC’s and a 500MHz QVCO. The requirements for the ADC offset, QVCO phase noise and mixer linearity are rather relaxed, which enables a low-power implementation.

Correlation Between Electrode-Tissue Impedance and Motion Artifact in Biopotential Recordings

This paper presents an integrated ultra-low power analog frontend architecture for UWB impulse radio receivers. The receiver is targeted towards applications like wireless sensor networks and body-area networks typically requiring ultra energy-efficient, low data-rate communication over a relative short range. The proposed receiver implements pulse correlation in the analog domain to severely relax the power consumption of the ADCpsilas and digital backend. Furthermore a fully integrated prototype of the analog front-end, containing an analog pulse correlator, a linear-in-dB variable gain amplifier and a 4-bit ADC, is demonstrated. Several design decisions and techniques, like correlation with a windowed LO instead of with a matched template, exploiting the duty-cycled nature of the system, operation in the sub-1 GHz band as well as careful circuit design are employed to reach ultra-low power consumption. The analog front-end was manufactured in 130 nm CMOS and the active circuit area measures only 600 mum times 730 mum. A maximum channel conversion gain of 50 dB can be achieved. The AFE consumes 1.44 mA at 1.2 V power supply and operates at a pulse rate of 37.5 Mpulses per second. This corresponds to an energy consumption of 46 pJ/pulse which is by far best-in-class. A wireless link over more than 3.5 m in an office-like environment has been demonstrated which makes the proposed receiver well suited for the targeted applications.

DESIGN OF AN ENERGY-EFFICIENT PULSED UWB RECEIVER

This paper discusses an architecture for an integrated ultra-low power impulse radio receiver for low data rate applications such as biomedical sensor networks. Choosing a proper system architecture allows to implement a receiver with relaxed specifications for the typical building blocks which results in a low-power implementation. Furthermore a design in 130 nm CMOS of a fully integrated ultra-low power PLL, a critical block of such receivers, is presented. The PLL serves a double purpose. It acts as the master clock generator for the receiver and it is also used to generate a template waveform for pulse reception. The latter requires the PLL to have quadrature outputs since the receiver uses I/Q reception. Because rather relaxed specifications in terms of phase-noise are required, a differential ring VCO with an even amount of stages is a suitable topology. The VCO has a measured center frequency of 568 MHz and a tuning range of 23%. It achieves a phase-noise of -91 dBc/Hz @ 1 MHz offset. The PLL employs a divide-by-8 and locks to an externally applied 75 MHz clock. Measurements show a total power consumption less than 200 muW with an rms jitter of 24 ps on an output clock of 600 MHz.

A 46pJ/pulse analog front-end in 130nm CMOS for UWB impulse radio receivers

This paper gives an overview of RFID technology. RFID systems are described in general and a few example cases are given. After that the paper mainly focuses on the hardware requirements for RFIDs. Also Real Time Locationing Systems (RTLS) are discussed. This gives the title of the paper a double meaning: ‘what is the state of the art in RFID’ but also what is the available technology to come to locationing capable RFID systems. The paper gives an overview of the design challenges of different RFID systems. Also possible circuit solutions and directions are addressed.