@article{gadfort_franzon_2014, title={Millimeter-Scale True 3-D Antenna-in-Package Structures for Near-Field Power Transfer}, volume={4}, ISSN={["2156-3985"]}, DOI={10.1109/tcpmt.2014.2349983}, abstractNote={This paper describes the modeling, fabrication, and measurement of a method to construct true 3-D antennas for radio frequency (RF) power harvesting in millimeter-scale sensors. The goal is to create an omnidirectional RF power-harvesting structure, which can provide power even if the sensor and external power source are not perfectly aligned. Because the orientation of the sensor is not known in advance, the antenna must work equally well in all directions. To realize such a structure, antennas will be built into the packaging of the sensor, and this allows for the largest possible antenna without increasing the size of the sensor and by combining antennas which are orthogonal to each other. This construction results in a cubic structure, where the power-transfer efficiency can be increased by 22 dB over a traditional single-coil setup at the worst case orientations for the sensor. The presented structures will range from 3 to 5 mm cubes.}, number={10}, journal={IEEE TRANSACTIONS ON COMPONENTS PACKAGING AND MANUFACTURING TECHNOLOGY}, author={Gadfort, Peter and Franzon, Paul D.}, year={2014}, month={Oct}, pages={1574–1581} }
 @inproceedings{zhao_gadfort_erickson_franzon_2013, title={A compact inductively coupled connector for mobile devices}, DOI={10.1109/ectc.2013.6575919}, abstractNote={A nested inductive connector, consisting of a single power channel and one or more data channels, is proposed as replacement for legacy conductive connectors in mobile devices. Advantages include minimized space in the mobile device, waterproofing, orientation independence, and resistance to stress through a breakaway mechanism. A simulation and analysis of relevant parameters, such as the transfer coefficients for both the power and data channels as well as crosstalk, of the connector design for a simple 2-layer PCB is presented. As an example, the proposed connector is utilized as a replacement for a standard TRS headphone jack found on many mobile devices. The connect or features an AC to DC rectifier, data transmitting circuits, as well as a Class-D power amplifier to drive a pair of headphones.}, booktitle={2013 IEEE 63rd Electronic Components and Technology Conference (ECTC)}, author={Zhao, W. X. and Gadfort, P. and Erickson, E. and Franzon, Paul}, year={2013}, pages={2385–2390} }
 @inproceedings{ledford_gadfort_franzon_2012, title={An analysis of subthreshold SRAM bitcells for operation in low power RF-only technologies}, DOI={10.1109/subvt.2012.6404316}, abstractNote={Current RFID systems rely on the RF transciever to transmit information and convert RF power to DC to operate any integrated digital circuits. Research investigating the application of RF signals directly on digital CMOS circuits without RF-DC conversion is an emerging area for RFID technologies. One crucial digital circuit for most RFID systems is memory, needed for storing operational instructions and sampled data. An in-depth study and comparison of subthreshold SRAM bitcells has been conducted to analyze how such memories will function in a subthreshold RF-only regime without the need for RF-DC conversion. Several SRAM cells were chosen for conversion into the RF-only family and measured against several metrics, including highest performance at lowest operating voltage, power consumption, and static noise margins (SNM). Including RF supply transistors, an 18-T subthreshold RF-only bitcell is proposed, capable of operating at a data rate of 100 kHz at VRF of 200mVRMS.}, booktitle={2012 IEEE subthreshold microelectronics conference (SUBVT)}, author={Ledford, J. and Gadfort, P. and Franzon, Paul}, year={2012} }
 @inproceedings{gadfort_franzon_2012, title={Design, modeling, and fabrication of mm(3) three-dimensional integrated antennas}, DOI={10.1109/ectc.2012.6249081}, abstractNote={This paper describes the design, modeling, and fabrication methods of a new method to build three-dimensional integrated antenna arrays. The goal is to create a mm-scale sensor for implantation in the human body. Since the orientation of the sensor is not known in advance the antenna must work equally well in all directions. The best way to do this is to build antennas on each side of a cubic structure. The antenna is intended for near field power harvesting. By utilizing the edge antenna the power transfer efficiency can be increased by 18.9 dB at even the worst orientations for the sensors. Another application would be to create an omnidirectional antenna for high frequency mobile devices.}, booktitle={2012 IEEE 62nd Electronic Components and Technology Conference (ECTC)}, author={Gadfort, P. and Franzon, Paul}, year={2012}, pages={1794–1799} }
 @inproceedings{gadfort_franzon_2012, title={Near threshold RF-only analog to digital converter}, DOI={10.1109/subvt.2012.6404321}, abstractNote={This paper describes an analog-to-digital converter (ADC) capable of operating in a RF-only circuit topology. A major limitation to direct RF-powered sensors are the lack of analog circuits. The proposed architecture is comprised of a cross-coupled pair of inverters, which act as the comparator for the ADC. This setup has been simulated in IBMs 0.13 μm bulk CMOS process for a 3 bit analog-to-digital converter (ADC). At a RF supply voltage of 300 mVRMS and frequency 13.57 MHz, the ADC has a resolution of 20 mV and can resolve voltages ranging from -80 mV to 80 mV, and at a frequency of 915 MHz the ADC can resolve voltages ranging from -140 mV to 140 mV. In order to optimize the ADC operation, the sampling time has been adjusted to one-third of the evaluation time, to give the comparator enough time to complete the amplification.}, booktitle={2012 IEEE subthreshold microelectronics conference (SUBVT)}, author={Gadfort, P. and Franzon, Paul}, year={2012} }