A 0.8 V, 14.76 nVrms, Multiplexer-Based AFE for Wearable Devices Using 45 nm CMOS Techniques

Abstract

Wearable medical devices (WMDs) that continuously monitor health conditions enable people to stay healthy in everyday situations. A wristband is a monitoring format that can measure bioelectric signals. The main part of a wearable device is its analog front end (AFE). Wearables have issues such as low reliability, high power consumption, and large size. A conventional AFE device uses more analog-to-digital converters, amplifiers, and filters for individual electrodes. Our proposed MUX-based AFE design requires fewer components than a conventional AFE device, reducing power consumption and area. It includes a single-ended differential feedback operational transconductance amplifier (OTA) and n-pass MUX-based AFE circuits which are related to the emergence of low power, low area, and low cost AFE-integrated chips that are required for wearable biomedical applications. The proposed 6T n-pass multiplexer measures a gain of −68 dB across a frequency range of 100 kHz with a 136.5 nW power consumption and a delay of 0.07 ns. The design layout area is approximately 9.8 µm2 and uses 45 nm complementary metal oxide semiconductor (CMOS) technology. Additionally, the proposed single-ended differential OTA has an obtained input referred noise of 0.014 µVrms, and a gain of −5.5 dB, while the design layout area is about 2 µm2 and was designed with the help of the Cadence Virtuoso layout design tool.

A Current-Mode Analog Front-End for Capacitive Length Transducers in Pneumatic Muscle Actuators

“…The structure of this Capacitive-MKM (C-MKM) overcomes the drawbacks intrinsic of the abovementioned solutions since it: (i) directly measures the distance between the two ends of the muscle without the need of mechanical sensors; (ii) does not suffer from external electrical and magnetic disturbances; (iii) is easy to be mounted between the two muscle end caps; (iv) respects the compliance of MKM muscles. To take full advantage of the properties of the C-MKM, the present paper aims to describe the design, implementation, and characterization of a Capacitance-to-Voltage Analog-Front-End (CV-AFE) circuit capable of measuring the value of the C-MKM capacitance whose output voltage is directly proportional to the pneumatic muscle length during both its elongation and contraction phases in real-time [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. In particular, CV-AFE circuits are employed in a large variety of medical [ 24 , 25 , 26 , 27 , 37 , 39 ] and industrial [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ] applications.…”

“…To take full advantage of the properties of the C-MKM, the present paper aims to describe the design, implementation, and characterization of a Capacitance-to-Voltage Analog-Front-End (CV-AFE) circuit capable of measuring the value of the C-MKM capacitance whose output voltage is directly proportional to the pneumatic muscle length during both its elongation and contraction phases in real-time [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. In particular, CV-AFE circuits are employed in a large variety of medical [ 24 , 25 , 26 , 27 , 37 , 39 ] and industrial [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ] applications. The integration of analog and digital electronic paradigms identifies the Capacitance-to-Digital Converters (CDC) that enable efficient digital data processing and data transmission [ 24 , 25 , 29 ].…”