A Source Switched Bio-Potential Amplifier with Thermal Noise Floor Reduction And Real-Time Settling DSL

Abstract

The increasing need for reliable interfacing between physiologic signals and electronic circuits has driven the need to explore low power and low noise circuits. The applications in the medical field are numerous, such as seizure detection and cardiac signal monitoring, among other examples. Bio-potential amplifiers for the wearable environment have several challenging requirements: 1) low noise, 2) low power, 3) dynamic offset cancellation and 4) time-and-space-varying DC offset cancellation. Several works have tackled these problems, however, low power analog techniques to tackle thermal noise reduction have been largely left untouched. Given that EEG signals are in µV range, integrated input-referred noise in the sub-µVrms range is desirable. Also, since the signal BW starts from as low as 0.5Hz, removing DC offset while keeping the signal BW intact is very crucial. DC Servo Loop (DSL) can mitigate the offset, but due to its low high-pass corner frequency, its settling time may take very long, and in particularly wearable environment, where DC offset can vary rapidly over time, such long settling time is undesirable. To resolve issues above, this paper introduces a Source-Switched a Chopper Stabilized- Instrumentation Amplifier (SSCS-IA) with a 4-Level Real-Time Settling (RTS)-DSL. The source switching technique results in a thermal noise floor reduction of 24%, and RTS-DSL aids in active control of the loop settling time to track and remove the rapidly varying DC offset in real-time

Date of Award	Dec 2016
Original language	American English
Supervisor	Jerald Yoo (Supervisor)