Andoni Beriain

A passive UHF RFID pressure sensor tag with a 7.27 bit and 5.47pJ capacitive sensor interface

A full passive UHF pressure RFID tag is presented in this work. Special attention is paid to the novel capacitive sensor-interface and the analog FE which were designed and implemented on a low cost 0.35µm standard CMOS technology. The characterization of the fabricated sensor interface connected to a pressure MEMS transducer shows a fully digital output with an ENOB of 7.27 bits and an FOM of 5.47pJ. The fabricated analog front-end, assembled to a matched dipole antenna, was connected to the digital core and the implemented pressure sensor. The RFID pressure sensor tag was characterized inside a PVC pressure chamber. Successful ID and pressure measurement (30kPa–120kPa) communication with a commercial RFID reader over a distance of 1.5m was achieved using the EPC Gen 2 standard. These characteristics allow the use of the proposed system in long range wireless pressure sensing and motivates the implementation of the proposed capacitive sensor interface in passive wireless sensors.

UHF RFID Temperature Sensor Assisted With Body-Heat Dissipation Energy Harvesting

The number of wireless medical wearables has increased in recent years and is revolutionizing the current healthcare system. However, the state-of-the-art systems still need to be improved, as they are bulky, battery powered, and so require maintenance. On the contrary, battery-free wearables have unlimited lifetimes, are smaller, and are cheaper. This paper describes a design of a battery free wearable system that measures the skin temperature of the human body while at the same time collects energy from body heat. The system is composed of an UHF RFID temperature sensor tag located on the arm of the patient. It is assisted with extra power supply from a power harvesting module that stores the thermal energy dissipated from the neck of the patient. This paper presents the experimental results of the stored thermal energy, and characterizes the module in different conditions, e.g., still, walking indoors, and walking outdoors. Finally, the tag is tested in a fully passive condition and when it is power assisted. Our experimental results show that the communication range of the RFID sensor is improved by 100% when measurements are done every 750 ms and by 75% when measurements are done every 1000 ms when the sensor is assisted with the power harvesting module.

Layout-aware design methodology for a 75GHz power amplifier in a 55nm SiGe technology

This paper describes a method to design mmW PAs, by modeling the electromagnetic behavior of all the passive structures and the layout interconnections using a 3D-EM solver. It allows the optimization of the quality factor of capacitors (Q-factors>20 can be obtained at 80GHz), the access points and arrangement of the power transistor cells. The method is applied to the design and optimization of an E-Band PA implemented in a 55nm SiGe BiCMOS technology. The PA presents a maximum power gain of 21.7dB at 74GHz, with a 3-dB bandwidth covering from 72.6 to 75.6GHz. The maximum output P1dB is 13.8dBm at 75GHz and the peak PAE is 14.1%. Method for layout-aware design and optimization of millimeter-wave PAs.Custom MOM capacitors with Q>20 at mm-wave frequencies are designed.The power transistor arrangement, access points and connections are optimized.The method has been applied to the design and optimization of a low-E-Band PA. Its most significant parameters (power gain, bandwidth, output 1dB compression point and efficiency) have been measured and compared to simulation results, with good agreement between them. The PA presents a maximum power gain of 21.7dB at 74GHz, and the 3-dB bandwidth covers from 72.6 to 75.6GHz. The maximum output P1dB is 13.8dBm at 75GHz, with a peak PAE at this point of 14.1%. These performance metrics are comparable to other state-of-the-art devices and make the PA capable of transmitting multi-gigabit signals over E-band wireless links.The method has been applied to the design and optimization of a low-E-Band PA.There is good agreement between simulation and measurement results.The performance metrics are comparable to other-state-of-the-art PAs.

A very low power 7.9 bit MEMS pressure sensor suitable for batteryless RFID applications

There is a strong motivation for the development of new low power sensors for wireless passive applications such as RFID. In this work, a combination of a MEMS capacitive pressure transducer and a capacitive to digital converter compatible with a sensor enabled RFID tag are presented. The MEMS transducer has been designed and fabricated using a MetalMUMPs process. Its characterization showed an output variation between 9.3 pF and 13.4 pF corresponding to a pressure variation between 0 kPa and 30 kPa, with a INL of 0,2%. On the other hand, the capacitance to digital converter has been implemented in a low cost 2P4M 0.35μm CMOS standard process. The interface measurements showed a resolution of 7.8 bit and an average power consumption of 16.56 μW. Combining both devices together with a sensor enabled RFID tag, a long range passive RFID sensor for pressure measurements up to 30 kPa could be implemented.

A robust, −40° to +150°C wireless rotor temperature monitoring system based on a fully passive UHF RFID sensor tag

A novel wireless temperature monitoring system for electric machines is presented based on fully passive UHF RFID sensor tags. The system is composed of a custom designed IC UHF RFID sensor tag connected to an external μP and ADC through a master-slave series-peripheral interface (SPI) connection. The sensing element is a NTC 10kOhm thermal resistor (-40° to 300°C). The sensor tag, which includes an optimized meander dipole antenna, an analog front-end with a power consumption of 4.3uA and a digital core, communicates the temperature value to two EM optimized PIFA antennas located inside the stator of the electrical machine. The signal received by the PIFA antennas is demodulated by a commercial 1W RFID reader. The sensor is able to sense from -40° to 150°C and robust to the presence of the high electromagnetic disturbances generated by the electrical machine. Measured data rates are higher than 1 sample per second.

Digital output MEMS pressure sensor using capacitance-to-time converter

In this paper, a MEMS capacitive pressure sensor and a capacitance to digital converter are presented. The MEMS transducer has been designed and fabricated using MetalMUMPs process from MEMSCAP. For an diaphragm area of 600×600 μm2 and an electrostatic pressure variation up to 30 kPa, the MEMS exhibits a capacitance change from 9.3 pF to 13.4 pF, with a INL of 0.2% A capacitance to digital converter has been designed and fabricated in a low cost 2P4M 0.35μm CMOS standard process as a digital interface to the MEMS sensor. The measured resolution of 7.9 bit and power consumption of 16.56 μW demonstrate that by combining both devices a long range passive RFID sensor for pressure measurements up to 30 kPa is achieved.

0.5 V and 0.43 pJ/bit Capacitive Sensor Interface for Passive Wireless Sensor Systems

This paper presents an ultra low-power and low-voltage pulse-width modulation based ratiometric capacitive sensor interface. The interface was designed and fabricated in a standard 90 nm CMOS 1P9M technology. The measurements show an effective resolution of 10 bits using 0.5 V of supply voltage. The active occupied area is only 0.0045 mm2 and the Figure of Merit (FOM), which takes into account the energy required per conversion bit, is 0.43 pJ/bit. Furthermore, the results show low sensitivity to PVT variations due to the proposed ratiometric architecture. In addition, the sensor interface was connected to a commercial pressure transducer and the measurements of the resulting complete pressure sensor show a FOM of 0.226 pJ/bit with an effective linear resolution of 7.64 bits. The results validate the use of the proposed interface as part of a pressure sensor, and its low-power and low-voltage characteristics make it suitable for wireless sensor networks and low power consumer electronics.

Vital Sign Sensing Technology

The four physiological measures of body temperature, pulse rate, respiration rate and blood pressure have for a long time been considered as vital signs in the diagnosis of a patient’s health. It is also widely accepted that the routine measurement of other physiological or biological signals, possibly pathology specific, would help considerably in diagnosis and early stage treatment. Such measurements might include, for example, heart activity, brain activity, blood glucose level or mobility. Furthermore, the development of portable systems that can make a number of different health related measurements would prove beneficial in the monitoring of patients during treatment, recovery or rehabilitation. Technologies and instruments that can make these measurements have existed for some time, but factors such as their cost, lack of portability and in some instances, a requirement for expert knowledge, have restricted their wide scale use. Today, however, advances in information technology, communications and microfabrication techniques have made possible the realisation of truly portable systems for the measurement of a wide range of physiological signs at any medical intervention. This chapter describes the sensing technologies and systems currently being developed, or that are in use, for the measurement of a new, larger range of vital signs.

A 0.6V and 0.53µW nonius TDC for a passive UHF RFID pressure sensor tag

This work presents a full passive UHF RFID pressure sensor tag which uses a nonius based TDC capacitive sensor interface. The proposed converter has a fully digital output and allows reducing power consumption while maintaining the required resolution. The nonius based TDC has been designed using TSMC 90nm standard CMOS technology. Post-layout simulations show that the converter presents a 12 bit resolution and 9 effective bits in the time range from 10μs to 40μs when VDD varies in the range from 0.55V to 0.7V and temperature variations in the range from 0°C to 60°C are considered. The maximum measurement time is 49.9μs and the average power consumption of the converter is 0.53μW at 10 samples per second from a 0.6V voltage supply.

A CMOS sensor signal conditioner for an automotive pressure sensor based on a piezo-resistive bridge transducer

This paper describes the design of a Sensor Signal Conditioner for a pressure sensor transducer in automotive applications. The circuit has been implemented in a 0.35 um CMOS process and comprises an Instrumentation Amplifier (IA), a 2nd order Chebyshev active low pass filter and an 1st order incremental ADC. The IA consumes 3mA with a supply voltage of 5V. Measured gain is 30 dB with 10° of phase margin. The PSRR and CMRR are 60 dB and 90 dB, respectively. Measured input referred offset voltage is 22 uV. The IA shows good linearity up to an amplitude of 2.5 Vpp at the output. With this output swing of 2.5 Vpp harmonics are 60dBc for a 1 KHz input tone. The PSD of the input referred noise is below 150 nV/VHz. The ADC current consumption of the ADC is 1.3 mA at 400 S/s. Its INL ±2.5 LSB for a 13 bit resolution, which gives an ENOB of 11.4 bits. Input referred noise results in 0.85 LSB or an ENOB of 11.4 bits. The IA combined with the ADC has an overall area of 0.71 mm2. Its INL of ±4 LSB. Again, the input referred noise is in 0.85 LSB or 11.5 bits.