Hannes Reinisch

A Multifrequency Passive Sensing Tag With On-Chip Temperature Sensor and Off-Chip Sensor Interface Using EPC HF and UHF RFID Technology

State-of-the-art passive RFID tags are limited in terms of functionality and operating range due to the limited power that can be converted from the electromagnetic field. This is why state-of-the-art wireless sensor systems are mostly battery-based if a high operating range is required. The proposed ultralow-power on-chip sensor unit and off-chip sensor interface which provides enough energy to supply various sensors with a power consumption up to the milliwatt range make it possible to remotely power the proposed RFID tag and use it as wireless sensor node. Equipping sensor nodes with RFID functionality not only enables identification and logistic applications but also an easy integration of the sensing tag into existing RFID systems. Exploiting the different characteristics of HF and UHF RFID systems, namely the large operating range in UHF and the high available power in HF, increases the flexibility and applicability of wireless sensor nodes. This paper presents a remotely powered multifrequency sensing tag according to the EPC HF and EPC Class 1 Gen 2 UHF standard developed in a 0.13-μm low-cost CMOS process. Input powers of -10.3 or -7.9 dBm at a frequency of 900 MHz are necessary to operate the sensing tag with activated on-chip sensor unit or off-chip sensor interface, respectively.

An Electro-Magnetic Energy Harvesting System With 190 nW Idle Mode Power Consumption for a BAW Based Wireless Sensor Node

State-of-the-art wireless sensor nodes are mostly supplied by batteries. Such systems have the disadvantage that they are not maintenance free because of the limited lifetime of batteries. Instead, wireless sensor nodes or related devices can be remotely powered. To increase the operating range and applicability of these remotely powered devices an electro-magnetic energy harvester iPs developed in a 0.13 μ m low cost CMOS technology. This paper presents an energy harvesting system that converts RF power to DC power to supply wireless sensor nodes, active transmitters or related systems with a power consumption up to the mW range. This energy harvesting system is used to power a wireless sensor node from the 900 MHz RF field. The wireless sensor node includes an on-chip temperature sensor and a bulk acoustic wave (BAW) based transmitter. The BAW resonator reduces the startup time of the transmitter to about 2 μs which reduces the amount of energy needed in one transmission cycle. The maximum output power of the transmitter is 5.4 dBm. The chip contains an ultra-low-power control unit and consumes only 190 nW in idle mode. The required input power is -19.7 dBm.

Highly efficient multistandard RFIDs enabling passive wireless sensing

This paper presents a highly efficient analog multistandard frontend for passive sensor-enabled RFID transponders. The CMOS only frontend is implemented in a 0.13 µm CMOS technology. The measured overall RF-to-DC power conversion efficiency of the analog frontend for a DC output power of 10 µW is about 7% and the maximum efficiency is about 15% at UHF. An implemented sensor interface consumes 1.4 µA at 1V supply. This interface contains an ultra low-power successive approximation ADC that uses the capacitive charge redistribution technique for its integrated DAC.

A 7.9μW remotely powered addressed sensor node using EPC HF and UHF RFID technology with −10.3dBm sensitivity

The combination of remote powering and wireless data transmission enables the monitoring of data in harsh and difficultly accessible environments, where batteries cannot be replaced or where it is not possible to supply the sensor system by wire or by thermal or photovoltaic energy harvesting. Equipping sensor nodes with RFID functionality not only enables identification and logistic applications but also an easy integration of the sensing tag into existing RFID systems. Exploiting the different characteristics of HF and UHF RFID systems, namely the large operating range in UHF and the high available power in H F, increases the flexibility of wireless sensor nodes.

An electro-magnetic energy harvester with 190nW idle mode power consumption for wireless sensor nodes

To increase the operating range and applicability of remotely powered devices an electro-magnetic energy harvester is developed in a 0.13 µm low cost CMOS technology. The presented system converts RF power to DC power to supply wireless sensor nodes, active transmitters or related systems with a power consumption up to the mW range. The chip includes an ultra low power control unit and consumes only 190 nW in idle mode. The input sensitivity is −19.7 dBm.

Measurement methods for power requirements of high performance UHF RFID tags

The sensitivity parameter is one of the most important parameters characterizing UHF RFID tags. This paper presents methods for measuring this parameter. It focuses on the use of non-expensive laboratory equipment. Nevertheless, the proposed methods provide accurate results. Losses and behavior of the setup are calculated and described in detail. Single-ended and differential structures are distinguished and handled separately. Since the antenna plays an important role, its behavior is also considered. Still, the measurement setup is contact based.

A fully EPC compatible multi frequency passive RFID tag with −11.4 dBm sensitivity

This paper presents a fully passive multi frequency RFID transponder according to the EPC HF and EPC Class 1 Gen 2 UHF standard. The combination of inductive and electro-magnetic coupling increases the applicability and flexibility of state-of-the-art RFID transponders especially for these areas of applications where RFID transponders should operate in both the HF and the UHF RF field. An easy integration into existing systems makes the multi frequency transponder competitive on the market because commercial HF and UHF readers can be used. Only two input pins are necessary to connect the chip to a broadband antenna by using the concept of combining a balanced HF and an unbalanced UHF frontend. The chip operates from 13.56MHz to 2.45GHz and is developed in a 0.13 µm low cost CMOS technology.

A sub 1V self clocked switched capacitor bandgap reference with a current consumption of 180nA

This paper presents a bandgap reference capable of operating at supply voltages below 1V. In contrast to the vast majority of bandgap circuits the multiplication of the proportional to absolute temperature voltage is done by a switched capacitor network. Thus a reduced chip area is achieved. As a clock is needed for the switching, a relaxation oscillator is deeply integrated into the circuit. Combined the circuits provide a continuous sub bandgap voltage reference output of 615mV and a clock signal with a frequency of roughly 53kHz. The overall current consumption is 180nA at room temperature. The circuit is developed in a 130nm CMOS technology and occupies an active area of 0.0132mm2.

A 2-pin input multi frequency power scavenging unit for wireless sensor nodes and RFID tags

This paper presents a multi frequency power scavenging unit dedicated but not exclusively designed for supplying RFID transponders and wireless sensor nodes. The power scavenging unit converts the incoming AC power into DC power (from 1MHz up to 2.45GHz). The circuit is used in a fully-passive multi frequency RFID transponder according to the EPC HF and EPC Class 1 Gen 2 UHF standard and is developed in a 0.13 µm low cost CMOS technology. A new concept is utilized to combine a balanced HF and an unbalanced UHF frontend to harvest energy from the magnetic or electro-magnetic field.

An ultra-low power voltage regulator for wireless sensor nodes

This paper presents an ultra-low power voltage regulator used for low power wireless sensor nodes. As the input conditions for these types of regulators can be quite different in terms of voltage range and transient speed, the introduced architecture is designed to be almost insensitive to these variations. Even if the pass device is formed by an NMOS transistor, low-dropout operation is possible by the utilization of a charge pump. The focus is on reducing the energy consumption of the regulator while keeping the robustness high. The regulator does not need an external compensation device. The circuit, implemented in a 0.13 µm CMOS process, generates the supply voltage for an ultra-low power temperature sensor and an ADC. Implementation and experimental results are discussed.