What if the biggest breakthrough in semiconductor power efficiency came from operating transistors below their normal limits?
That’s exactly what Ambiq achieved with SPOT® (Subthreshold Power Optimized Technology), a patented platform that reimagines how chips consume energy. By leveraging the physics of subthreshold operation, SPOT has transformed what’s possible in ultra-low-power computing and opened the door to a new era of smart, sustainable devices.
In this blog, we’ll explain how subthreshold technology operates, the challenges associated with it, and how designers can use it in real-world applications.
Rethinking How Transistors Work
In a standard chip, each transistor acts like a tiny switch. It turns “on” when enough voltage is applied (anything above 1 volt) and “off” when that voltage drops below a threshold (anything below 1 volt), with no in-between.
However, even below that threshold, a small amount of current still leaks through. Usually, that’s seen as wasted energy or something to eliminate. Ambiq flipped that idea on its head. Instead of battling that leakage, we discovered a way to utilize it.
By operating our circuits in this ultra-efficient “subthreshold” region, Ambiq’s Apollo chips perform the same computing tasks with dramatically less energy, because energy is voltage squared —so the lower you drop the power, the less energy it takes. This often results in devices that consume up to 10× less power than traditional circuit designs.
Ambiq turned what others saw as a design flaw—subthreshold leakage—into an opportunity for revolutionary energy efficiency for battery-powered devices. So if subthreshold power is so great for semiconductors, why doesn’t everyone do it?
The Challenge of Subthreshold Operations
Operating below the threshold voltage isn’t easy. At such low power levels, even minor environmental changes can produce significant effects:
- Temperature: A few degrees can change current flow.
- Voltage: Tiny fluctuations can shift performance.
- Manufacturing: Microscopic variations can alter transistor behavior.
- Mechanical stress: Vibration or strain can impact reliability.
In short, addressing these challenges is time-consuming and hard to implement outside of research laboratory settings. Semiconductor companies didn’t think subthreshold operations were scalable, so they continued to build upon what they knew worked. And for many device manufacturers, an incremental increase in battery life or processing capabilities was better than nothing.
But in the age of AI, where every microjoule matters, harnessing subthreshold computing in a way that is practical and scalable would pay large dividends to device manufacturers, not only in energy efficiency but also in performance and intelligent features. Developing a completely new approach to designing, testing, and stabilizing circuits is exactly what Ambiq set out to do with the SPOT platform.
Commercialization at Scale
SPOT is not just a single invention; It’s a complete system of patented techniques, proprietary circuit designs, and process improvements that make subthreshold operation commercially feasible—and Ambiq is the only semiconductor company to build it at scale.
SPOT is the core technology behind Ambiq’s Apollo family of microcontrollers and SoCs, used in 280 million devices worldwide. Everything from personal products such as wearables and hearables to smart home systems, industrial sensors, and edge AI devices.
Each generation of Apollo chips delivers more capability, more intelligence, and the same unmatched energy efficiency, proving that SPOT is not just a concept, but a production-proven technology platform.
Strategic Impact of SPOT
For technology leaders and business executives, SPOT is more than a technical achievement; it’s a strategic advantage in the arms race for the latest and greatest devices.
By cutting energy use by up to 10x, SPOT opens doors to entirely new markets and use cases. In the early years of smart devices, having a longer battery life was where SPOT excelled, but as devices transitioned to “intelligent,” having a longer battery life was just one of many considerations for manufacturers.
They want to build devices that are always-on—meaning they are continuously running data collection and processing in the background. They want to develop more intelligent devices with larger neural networks, giving their customers intelligence that moves beyond a “nice-to-have” feature into a “must-have feature.” They want sustainable devices that reduce energy waste and lower operating costs.
SPOT enables all of these use cases, resulting in smarter, smaller, always-on, and more sustainable products that help companies align innovation with efficiency and ESG goals. A favorite comment from customers is being told they can add intelligent features where there was none before, thanks to the power efficiency made available by SPOT.
The Future Runs on SPOT
Subthreshold operation represents a true shift in how we think about semiconductor design. Through SPOT, Ambiq has turned a once “impractical” idea into a scalable reality, powering real devices, real markets, and a more energy-efficient world.
As intelligence continues to move closer to the edge, power efficiency will define the next generation of computing. Ambiq’s SPOT platform ensures that performance, intelligence, and sustainability can advance together without compromise. Ambiq isn’t just redefining low power. We’re redefining what’s possible.
