REALIZING THE PROMISE: NEW TECHNOLOGY POWERING THE AUTOMOTIVE AND ENERGY SECTORS
The paradigm jump in IC manufacturing materials changes the game for many industries. These new ICs, led by Gallium Nitride (GaN) and Silicon Carbide (SiC), outperform silicon-based chips on several metrics. Their characteristics make them invaluable where high-speed switches must be reliable and durable at high voltage and temperature levels, all while using less energy.
A global desire for cleaner energy sources provides the push for electric vehicles/hybrid-electric vehicles (EV/HEVs). This move toward sustainability causes device testing requirements for both automakers and energy production equipment manufacturers to expand.
While the advantages of these new materials are substantial, deploying them into mass-produced consumer goods and widespread industrial devices poses some serious challenges. Namely, how do manufacturers adequately test large numbers of these devices in situations where profit margins are thin and reliability stakes extremely high?
The answer for many companies is to bring testing in-house with turnkey solutions from Accel-RF. Our test equipment is a cost-effective way for companies to perform accelerated life testing on chips with input voltages of up to 3 kV with currents as high as 25 amps. The systems are configured with multiple independent channels capable of programmable switching frequencies at temperatures up to 200 C. They also collect critical statistics, such as end-of-life reliability data and burn-in failure rates, and facilitate simplified reporting of the data.
AUTO’S MOVING TARGET
As society grows more mobile, people increasingly view their car’s interior as additional living space. Capitalizing on this, carmakers are designing dashboards that function as complete information and entertainment hubs, in sync with the user’s smartphone or other connected devices.
Wireless fast-charging systems based on GaN and SiC effortlessly replenish batteries of devices inside the vehicle. Designers are working on ways to use GaN or SiC devices to develop wireless recharging systems for the EV motor, as well.
Additionally, the auto-industry needs chips capable of high-frequency RF signal transmission for the development of increasingly more advanced sensing, autonomous driving and communication systems such as Vehicle to Everything (V2X). The growing demand from consumers for enhanced safety and convenience features in cars is as adamant as is their call for greener power.
The thousands of sensors present in cars operate in the E-band spectrum, which is above 24 GHz. At this high frequency, silicon-based IC switches are not able to withstand the demands of speed, accuracy, and reliability needed to ensure driver and passenger safety. Again, manufacturers turn to GaN and SiC for devices that can operate within the necessary parameters with no tolerance for failure.
IMPORTANT RELIABILITY PARAMETERS OF CONCERN
DC Bias Current
Active semiconductor components require a DC power supply to operate. The DC bias voltage and current levels are critical parameters as the power dissipation of each active element will contribute to temperature rise and drive overall efficiency.
RF Output Power
The RF output power of an amplifier drives the overall capabilities of a transmitter. The saturation level and how the output power of a device compresses with input power is used to determine which applications and systems are suitable for that device.
The ratio of RF power delivered to a load relative to the input power. How gain changes and compresses as these levels rise and approach saturation is critical to designing systems for any RF application.
Ohmic Contact Resistance
In semiconductors, this is the intrinsic resistance through the metalized terminals of the device into the channel or junction. A physical change in the ohmic contacts, which can be an effect of metal migration, can change the resistance and impact the electrical performance of a device.
IMD occurs when two signals are present in a nonlinear system, such as an amplifier. The frequency harmonics of these two signals mix and create 2nd and 3rd order intermodulation products. Measuring and mitigating these distortion levels are critical for communication applications.
Commonly referred to as “jitter”, phase noise is the random fluctuations of the phase of a signal source. It is present in oscillators and digital clocks and can have detrimental effects on a system where frequency conversion takes place. A signal with high phase noise can end up occupying more of the spectrum than intended and introduce error.
This is a critical parameter in all Receiver designs. The Noise Figure must be low for a system to be sensitive enough to detect and process weak signals. Low Noise Amplifiers (LNA) are typically the first element in a receiver and are designed to minimize Noise Figure.
For amplifiers in RF applications, this represents the relationship between the input power and the output power of a device. At low input power levels, linearity is uniformly quantified by the gain. As input drive increases, the device gain compresses as the device saturates and the linearity characteristics change.
Switching Response Time
The rise and fall time of RF switches used in high-frequency applications can set limitations on the bandwidth and other key aspects of a system. When used in a phased array, the switching speed can limit how quickly the beam can be steered, for example.
This represents the ability of a source, such as an oscillator, to maintain a constant frequency output. Outside influences such as temperature and change in bias voltage can lead to drift and affect frequency stability. Stability in communication systems is required so that a signal does not drift outside of its designated band.
The Automotive Industry’s history with RF systems has been historically focused on collision avoidance sensor development. Early collision avoidance systems were based on RF radar technology. Most of these systems utilized the 24 GHz and 77 GHz millimeter-wave frequency bands to achieve performance and implementation requirements. Going forward, the use of RF systems in cars will explode with the onset of the Automated Driving System. The Automated Driving System will depend on communication and/or cooperation with outside entities for sensory information to identify appropriate navigation paths, as well as obstacles and relevant traffic control signage. The self-driving automobile will communicate from vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and a growing list of entities that may affect, or may be affected by, the vehicle (V2X communication system).
Reliability testing is driven in this market by the following:
- Safety liabilities (risks) from failed system components in the network.
- Unrealized performance to expectation level (value).
- Maintenance cost (down-time) leads to inefficient system utilization.
- Performance consistency from unit to unit for effective deployment across a highly regulated market.
- Performance degradation with age would drive maintenance service costs and user dissatisfaction.
THE WAY TO MOVE FORWARD
Since this new era of automotive engineering and power production is just getting underway, the roles of the various players are still fuzzy. The government regulates the safe operation of these designs, but who invests in infrastructure to ensure safety and reliability is still a gray area.
A long history of statistical reliability data does not yet exist for GaN and SiC devices. It falls to the manufacturer to prove to both regulatory agencies and investors that proposed products will perform as predicted.
Accel-RF is actively involved with various standards committees, working to define testing protocols in this rapidly evolving part of the chip manufacturing industry. Accel-RF gives automotive and energy production equipment designers the confidence to move forward with product development now, even as these industries continue their rapid transformations.
By providing the latest innovations in flexible design and test solutions, Accel-RF is helping manufacturers create high-quality and high-performance products that meet the demand of safety and reliability in these two challenging sectors.
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