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Incremental Analog-to-Digital Data Converters

A potential application of the incremental ADC in a wearable device, and its integrated hardware implementation.

Wearable device are crucial to the Internet of Things (IoT), with more than 35 million connected wearable devices in use at the end of 2014. In wearable devices and other IoT applications, integrated sensor interface circuits are required to prepare the analog sensor output for digital signal processing. In some cases, such as image sensors and electroencephalograms (EEG), a single interface needs to be shared among many sensors. Often the sensors operate in battery-powered devices, and hence power dissipation in the interface circuitry is of great concern. The interfaces usually require high-accuracy ultra-low-power analog-to-digital converters (ADCs) with low signal bandwidth.

Incremental analog-to-digital converters (IADCs) represent an excellent choice for use in such sensor interfaces. They apply a combination of signal processing and noise shaping to achieve high accuracy. Their  sample-by-sample operation allows sharing a single ADC among multiple sensors.

CDADIC researchers have developed novel IADC architectures that achieved both high accuracy and excellent power efficiency. A particularly useful new IADC configuration was recently found, which reuses a single active component multiple times. This breakthrough hardware recycling technique extends the accuracy of the converter with very low power consumption. Compared to the conventional single-step IADC of the same accuracy. The new ADC reduces the power requirement by a factor of close to 1000.

Fabricated on an integrated chip, the novel device demonstrated superior performance. It offers a powerefficient realization for various integrated sensor interfaces used in industrial, medical and environmental applications.

Economic Impact:

The next big wave of data-driven technological innovation will connect physical devices embedded with tiny computing devices to the Internet. This will help advance wearable electronic systems and smart appliances in homes and offices. These has the potential to greatly improve the efficiency and safety of daily activities. As a result, it is predicted that there will be a rapidly growing market for sensor and micro-actuator interface devices, which require micro-power high-accuracy ADCs as their key components. The data converters developed under the proposed research will play important roles in such interfaces. There is considerable interest by high-technology companies in this work, as shown by grants and gifts received from several CDADIC companies (and many outside ones) to support more research in this field. Incremental analog-to-digital converters have been receiving attention in the many applications. They allow the translation of analog signals into digital form in a sample-by-sample manner, and are able to achieve high accuracy just like noise-shaping converters.

Since these converters can be multiplexed among many sensor channels, and require minimal amount of power using our hardware recycling technique, they represent excellent choices for wearable devices. The total number of connected devices in which our circuits may be used - including smart home appliances, “wearables,” smart metering systems, robots and autonomous vehicles. These are projected to grow to tens of billion by 2019. The integrated circuit industry will benefit from innovations in this field. The country will benefit by maintaining our global competitive advantage in the digital economy.

For more information, contact Gabor Temes,, 541.737.2979.

PDF icon CDADIC-2016.pdf