Due to pandemic concerns, Alphacore will participate virtually to present several papers and support poster sessions to showcase our latest radiation hardened high-performance data conversion products, and analog, mixed signal, RF electronic and cybersecurity innovations.
Also, please visit our virtual booth to say howdy!
Papers:
Advanced Power Electronics Session 4.4 entitled: Dynamic Reconfiguration Strategy for Solar Arrays on Spacecrafts Using eGaN Switches
The efficiency of spacecraft solar cells reduces over the course of their operation. Traditionally, they are configured to extract maximum power at the end of their life and not have a system which dynamically extracts the maximum power over their entire life. This work demonstrates the benefit of dynamic re-configuration of spacecraft solar arrays to access the full power available from the solar panels throughout their lifetime. This dynamic reconfiguration is achieved using enhancement mode GaN (eGaN) devices as the switches due to their low Ron and small footprint. This work discusses hardware implementation challenges and a prototype board is designed using components-off-the-shelf (COTS) to study the behavior of photovoltaic (PV) panels with different configurations of switches between the PV cells. The measurement results from the board proves the feasibility of the idea, showing the power improvements of having the switch structure. The measured on resistances are used to model GaN switches in a larger satellite system. Additionally, a CMOS controller integrated circuit (IC) in 0.18um technology has been developed to provide a small form factor solution that can be embedded in the solar cells on the spacecraft wing. The floating voltage required to drive eGaN switch is generated by an innovative switched-capacitor converter circuit, which dynamically tracks the PV cell voltage. The measurement results of this IC are detailed within this work.
Supply Chain Analysis. Session 14.4 entitled: RF Supply Chain Tracking via Multi-Variate ID Assignment
The integrated circuit (IC) design industry has adopted a globalized design and manufacturing flow where multiple teams contribute to the design of one IC, which gets fabricated in an off-site facility, and possibly tested in another. This paper describes methods for assigning and tracking unique IDs for RF ICs without resorting to additional circuitry. The proposed methodology utilizes performance and other parametric measurements under supply modulation and assigns IDs in a multi-variate manner while taking repeatability and reproducibility errors in measurements into account.
GaN Power Electronics. Session 23.3 entitled: A Novel Hybrid GaN/CMOS Rad-Hard DC to DC Converter Module
This paper presents a hybrid GaN/CMOS buck converter designed to achieve high efficiency and high conversion ratio, with low profile and high total dose radiation tolerance. This work is based on our previous work with switching frequencies of 4MHz to 15MHz and 88.6% measured peak efficiency with air-core off-chip inductor. This converter shall provide a load current over 10A and output voltage as low as 1V with input voltage of 18V. The gate driver and the controller are integrated within a single CMOS integrated circuit (IC). The closed-loop control of the converter is based on voltage mode control. The cascode gate driver is implemented with custom 3.3V enclosed-gate transistors, and employs an asymmetric high-side/low-side driver architecture to minimize losses. The power stage consists of a half-bridge GaN power module with synchronized GaN boot-strap circuits to achieve the maximum power stage efficiency. All power supplies for the controller/driver IC are generated directly from the 18V input with multiple on-chip regulators. Soft-start and under-voltage protection are also included on chip. The CMOS IC is designed in a commercial 0.35um high-voltage bulk CMOS process.
Poster Sessions:
Trusted, Assured and Cyber-Secure Microelectronics. P42.14 entitled: Novel Ionic Microsystem-Based Integrated Circuit Metering Solution
There is currently no direct, low cost, fast, and non-destructive method to determine how long an IC has been in operation. This hampers reliability studies and also means that used parts can be re-marked and sold as new, potentially endangering critical systems. We have developed a metering device that uses changes in capacitance caused by the controlled growth of a metallic electrodeposit on a solid electrolyte film over a sensing electrode. The capacitance is determined by the amount of charge supplied to the structure from a control circuit which is only active when the target IC is powered so that total IC run time can be determined. The electrodeposit is persistent and so the state of the device is preserved if the IC is powered down. The materials used in the device are compatible with CMOS fabrication and so the structure may be integrated into any IC.
Trusted, Assured and Cyber-Secure Microelectronics. P42.21 entitled: MEMS Accelerometer In-Field Recalibration Based on Incremental Electrical Stimulation Method
Micro Electro Mechanical Systems (MEMS) based accelerometers are one of the most commonly used sensors out there. They are used in devices such as, airbags, smartphones, airplanes, and many more. They are very accurate, however, they degrade with time or get offset due to damage over time. To fix this, they must be calibrated again using physical calibration technique, which is an expensive process to conduct. However, these sensors can also be calibrated infield by applying an on-chip electrical stimulus to the sensor. Electrical stimulus-based calibration could bring the cost of testing and calibration significantly down as compared to factory testing. An incremental change in physical parameters approach is proposed in this work. A prediction model with a root mean square error of 1% has been presented in this work. Experiments were conducted on commercially available accelerometers to test the delta change technique of electrical stimulus calibration.
