- CMOS temperature sensor
- Flash ADC
- Digital Low DropOut (LDO)
- True random number generator (TRNG)
- Random telegraph noise (RTN)
CMOS temperature sensor
The need for a low-power CMOS temperature sensor is increasing drastically. For any system, temperature monitoring is a must to ensure the operation safety. With the emergence of IoT, temperature sensors will be embedded all around us. This research continuously pushes the limit of accuracy, resolution, temperature range, and power consumption by inventing different circuit techniques. We focus on time-domain measurements for low-power operations. Recently, we have developed linear relationships between the current ratio and temperature by utilizing the intrinsic device mismatch. We are actively exploring utilizing device variability as a metric for temperature sensing. Our latest results show great promise as we can eliminate many sources of errors.
Analog-to-digital converters (ADC) are any system’s most important circuit blocks. The more we push for digitized systems, the importance of ADC increases. As the universe is analog, we need low-power ADC techniques for sensors, communication devices, and other devices. At present, we are focused on developing low-power flash ADCs. We aim to eliminate the energy waste required to deal with device mismatch by inventing fully on-chip digital calibration techniques. With the scaling of transistor dimensions, flash ADCs are expected to be used in a wide range of applications. Our research is creating the path toward that realization.
Power and supply management is a critical component that directly affects the energy efficiency and reliability of the system. Supply management is becoming more complex and power-hungry as we try to integrate more functional blocks into the same chip. In this research, we aim to develop digital LDOs that can quickly adapt to load activity without needing external signals and clocks. We are now focusing on using analog circuits to assist digital operation. The key is to ensure that the analog component is minimal and does not compromise the merits of digitization of power MOSFETs. We are adopting techniques with the self-adapting capability to tackle PVT variation.
True random number generator (TRNG)
The need for secure communication is also increasing with the increase of devices around us. True random number generators (TRNG) are essential circuits for secured communication and cryptography devices. We aim to develop a small-area and low-power TRNG that is robust to PVT variation. Achieving both small areas and low power is a challenge. We are pushing the limit with innovative ideas. Our goal is to create tiny TRNGs that can be embedded anywhere in a system on chip (SoC). These tiny TRNGs can then also be used as random sequence generators for stochastic computing. We are also exploring applications such as stochastic computing to realize adaptive computing.
Random telegraph noise (RTN)
Random telegraph noise (RTN) is fundamental to scaled transistors. In this research, we are measuring RTN-induced delay variability for scaled technology processes under low voltage operation.