Low-power and Biomedical Frontends
In this research area we focus on a variety of frontends where low power consumption and energy efficiency plays an important role, in particular we focus on biomedical applications. Both frontends for wireless communication and frontends for sensor interfacing are considered.
In today’s world, wireless communication in small, battery-powered devices is omnipresent. For instance: smart phones, tablets and watches with a plurality of wireless interfaces; wireless networks around the body; and smart-dust sensor nodes. Due to requirements in terms of small physical size, long battery lifetime, limited body-tissue heating, and increasing data rates, there is a continuous demand for improving energy efficiency. We are addressing these requirements in various ways, for instance:
- Smartness: by using adaptive non-linear components, self-interference of multi-standard radios can be greatly suppressed, leading to relaxed circuit requirements and better system performance.
- Wake-up radios: by using an extremely low-power wake-up radio next to a main radio, power can be saved during inactivity by suspending the power-hungry main radio.
- Beam-steering phased arrays: by means of an array of antennas, the directivity of wireless communication can be tuned perfectly from transmitter to receiver, thus avoiding power loss in other directions and improving spatial selectivity. We are developing circuits to implement these beam-steering systems.
- Optical-wireless communication systems: while wireless communication is often performed electromagnetically, optical solutions are becoming interesting to provide extremely high data rates. We thus develop systems that combine both forms of communication.
- Monolithic wireless sensors with energy harvesting: smart-dust applications require ~1mm3-size autonomous devices. This is only feasible if the whole system (including the sensor, the wireless communication with antenna, but also the energy harvesting & storage components) can be integrated on a single chip without external components. To achieve this, we develop system concepts and actual circuits that can implement all these functionalities with a very low power consumption.
Besides looking at wireless frontends, this research field of the MsM group also considers sensor front-ends. Again energy-efficiency plays a prominent role. Further, we focus on biomedical applications in particular. Apart from just circuit design, here we spend also effort to develop complete systems, demonstrators, and to acquire know-how of medical applications and signals. A few examples within this domain are:
- Power-efficient amplifiers and ADCs for fetal monitoring: fetal monitoring is extremely difficult due to the small signals of interest combined with large interferences. We are developing smart, reconfigurable circuits that can capture those signals reliably in a power-optimized way. We do this by combining reconfigurable circuits with signal-processing algorithms.
- Interfaces for deep-brain-stimulation: in order to develop circuits for brain-stimulation electrodes, models are developed and experimentally verified. This knowhow is used to optimally design amplifiers and stimulation electronics.
- Wearable wireless sensor systems for health monitoring: tele-health applications require continuous monitoring of vital information, such as blood pressure and ECG. We develop low-power circuits for signal monitoring and wireless communication, as well as system demonstrators that can be used in real-life experiments.