A Low Power On-Chip Class-E Power Amplifier For Remotely Powered Implantable Sensor Systems

This paper presents a low power fully integrated class-E power amplifier and its integration with remotely powered sensor system. The class-E power amplifier is suitable solution for low-power applications due to its high power efficiency. However, the required high inductance values which make the on-chip integration of the power amplifier difficult. The designed power amplifier is fully integrated in the remotely powered sensor system and fabricated in 0.18 mu m CMOS process. The power is transferred to the implantable sensor system at 13.56 MHz by using an inductively coupled remote powering link. The induced AC voltage on the implant coil is converted into a DC voltage by a passive full-wave rectifier. A voltage regulator is used to suppress the ripples and create a clean and stable 1.8 V supply voltage for the sensor and communication blocks. The data collected from the sensors is transmitted by on-off keying modulated low-power transmitter at 1.2 GHz frequency. The transmitter is composed of a LC tank oscillator and a fully on-chip class-E power amplifier. An additional output network is used for the power amplifier which makes the integration of the power amplifier fully on-chip. The integrated power amplifier with 0.2 V supply voltage has a drain efficiency of 31.5% at -10 dBm output power for 50 Omega load. The measurement results verify the functionality of the power amplifier and the remotely powered implantable sensor system. The data communication is also verified by using a commercial 50 Omega chip antenna and has 600 kbps data rate at 1 m communication distance.

A remotely powered fully integrated low power class-E power amplifier for implantable sensor systems

Catherine Dehollain, Enver Gürhan Kilinç, Kerim Türe

This paper presents a fully integrated low power class-E power amplifier and its integration to remotely powered sensor system. The on-chip 1.2 GHz power amplifier is implemented in 0.18 A mu m CMOS process with 0.2 V supply. The implantable system is powered by using an inductively coupled remote powering link at 13.56 MHz. A passive full-wave rectifier converts the induced AC voltage on the implant coil into a DC voltage. A clean and stable 1.8 V supply voltage for the sensor and communication blocks is generated by a voltage regulator. On-off keying modulated low-power transmitter at 1.2 GHz is used for the transmission of the data collected from the sensors. The transmitter is composed of a LC tank oscillator and a fully on-chip class-E power amplifier. Compared to the conventional class-E power amplifiers, an additional network which reduces the on-chip area is used at the output of the power amplifier. The measurement results verify the functionality of the remotely powered implantable sensor system and the power amplifier. The integrated power amplifier provides -10 dBm output power for 50 Omega load with a drain efficiency of 31.5 %. The uplink data communication with a data rate of 600 kbps is established by using a commercial 50 Omega chip antenna at 1 m communication distance.

Springer2016

A System for Wireless Power Transfer and Data Communication of Long-Term Bio-Monitoring

Camilla Baj-Rossi, Cristina Boero, Sandro Carrara, Giovanni De Micheli, Catherine Dehollain, Seyedeh Sara Ghoreishizadeh, Enver Gürhan Kilinç, Franco Maloberti, Stefano Riario, Francesca Stradolini

A system for wireless power transfer and data communication of implantable bio-monitoring systems is presented. The proposed solution uses a servo-controlled power transmitter moved under the animal moving space. An x-y movable magnetic coil transmits the required power with a level able to keep constant the received energy by the bio-sensor system. The power is transferred via the optimized remote powering link at 13.56 MHz. The received AC signal is converted to DC voltage with a passive full-wave integrated rectifier and the voltage regulator supplies 1.8 V for the implantable sensor system. The sensor control and read-out circuit measures the current on the bio-sensors and transmit the data to the transmitter. The sensor data is transmitted to an external reader by a low-power OOK transmitter and received by a custom designed receiver at 869 MHz. The results are shown in a tablet computer in real time continuously. The long-term characterization of the implantable system is verified by a fully bio-compatible packaged implant with 30 days measurement. A complete prototype is also presented to prove the overall system performance with experimental in-vitro measurement.

Institute of Electrical and Electronics Engineers2015

Efficiency enhancement and frequency-tunable capability in linear CMOS RF power amplifiers for wireless applications

Paulo Augusto Dal Fabbro

This research work deals with the design of linear CMOS RF power amplifiers. Two important aspects are treated: efficiency enhancement and frequency-tunable capability. For this purpose, two different integrated circuits were realized in a 0.11 µm technology, each one addressing a different aspect. With respect to efficiency enhancement, a dynamic supply RF power amplifier was realized. The circuit was designed for an operating frequency of 5.2 GHz, but measurements were also performed at 2.4 GHz. The integrated circuit includes a class A amplifier and a high-efficiency, switched-mode modulator. It occupies an area of 1.35 mm2. Two-tone measurement results at 2.4 and 5.2 GHz showed that the system can deliver over 16 dBm (40 mW) linear output power with efficiencies of 22.7% and 12.6%, respectively. Compared to a constant 2.5 V supply operation, the power amplifier operating with the dynamic supply delivers higher linear output power. Moreover, a relative efficiency improvement of a factor of 2.3 at 2.4 GHz and of a factor of 1.6 at 5.2 GHz at low output power levels is achieved. OFDM measurements at 2.4 GHz demonstrated that for an EVM lower than 3% and for an equal output power of 11 dBm (12.6 mW), the absolute improvement in efficiency is over 3.2%. In this work we also propose a tunable impedance matching network for use in multiband RF power amplifiers. This novel network is based on coupled inductors. A frequency-tunable RF power amplifier using this network was designed for operation at 3.7 and 5.2 GHz. Simulation results for the complete system integrated in a CMOS technology showed good results. However, the frequency-tunable behavior could not be observed in the characterization of the integrated circuit because of the low coupling factor of the integrated coupled inductors. A hybrid implementation using the integrated CMOS power amplifier, a discrete commercial RF transformer and a discrete bipolar transistor to control the current in the secondary winding of the transformer was carried out. The circuit was designed for operation at 200 and 300 MHz. The measurements have shown that at 200 MHz a relative improvement in efficiency of a factor of 1.4 was achieved. Moreover, less distortion was generated with the proposed tunable output matching network. The hybrid implementation allowed us to demonstrate the feasibility of the frequency-tunable RF power amplifier based on coupled inductors.

EPFL2009

Efficiency enhancement and frequency-tunable capability in linear CMOS RF power amplifiers for wireless applications

Paulo Augusto Dal Fabbro

EPFL2009