用于可穿戴式身体声音监控的专用IC
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2021-03-14
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Dedicated ICs for Wearable Body Sound Monitoring
Zhaoyang Weng, Shaoquan Gao, Jingjing Dong, Kai
Yang, Hanjun Jiang, Fule Li, Zhihua Wang
Tsinghua National Laboratory for Info. Sci. & Tech.
Institute of Microelectronics, Tsinghua University
Beijing, China
Yanqing Ning, Xinkai Chen
Ecore Technologies Ltd.
Beijing, China
Abstract—A highly integrated chipset for wearable wireless
body sound sensor is presented. It consists of a body sound sensor
readout chip and a 400M-440MHz short range wireless
transceiver chip. The sensor readout chip consists of a
programmable preamplifier and an over-sampling ADC, and it
consumes no more than 80μA current from 1.2V power supply.
In the transceiver chip, the transmitter adopts a direct up-
conversion architecture and delivers +6dBm maximum output
power. The receiver employs zero-IF architecture, and it achieves
a sensitivity of -93dBm @ 1Mbps MSK modulation. A body
sound sensor prototype has been implemented using this chipset.
Keywords—smart sensor, heart sound, wireless transceiver,
preamplifier, ADC
I. INTRODUCTION
One typical long-term human body information recording
system is the wearable wireless body sound sensing and
recording (SAR) system [1] which can be applied to trace
human body health conditions through body sound monitoring.
The smart sensor consists of a sound sensing device, a battery,
a wireless transceiver, along with a flow controller. There are
some critical challenges in implementing the wearable smart
sensor. The form factor of sensor, the power consumption and
the achievable data rate limit are the major concerns.
To assemble the sensor using off-the-shelf components, it is
inevitable to use a bunch of discrete components and
integrated circuits (ICs), including a sensor readout IC, a
wireless transceiver IC, a micro-controller unit (MCU), a
memory IC, several power management ICs and so on. The
size of wearable sensor cannot be minimized with off-the-
shelf ICs.
Furthermore, the available commercial transceiver chips
either consume too much power or provide quite limited data
rate which is not suitable for real-time body sound data
transmission. The expected sensor sampled the signals with a
16bit, 16kS/s ADC and the wireless transceiver is thus
supposed to support an effective throughput no less than
256kbps. A commercial Wi-Fi transceiver [2] usually
consumes hundreds of milliwatts power which is not
acceptable for wearable smart sensors using miniature
batteries. The state-of-the-art BLE transceivers consume
<20mA current, but the actual throughput is much less than
100 kbps [3], which can hardly be used for real-time body
sound data transmission. In addition, the commercial body
sound sensor (microphone) with adequate dynamic range and
data conversion resolution/rate consumes more power than
expected.
A highly integrated chipset with optimized throughput and
power consumption has been designed in this work for human
body sound sensor in the SAR system. It includes a sound
sensor readout IC with 16 bits resolution at a sampling rate of
16k samples/second and a short-range wireless transceiver IC
working at 400M-440MHz frequency band. The two chips as
well as an EEPROM chip are assembled in a SiP package,
with a size of 10*10*1 mm
3
. A body sound sensor prototype
has been built with the proposed chipset and measurement has
been done on volunteers. As shown in Fig. 1, such a body
sound sensor can be used to monitor cardiopulmonary sounds,
fetal heart beat, etc.
The paper is organized as follows. The overall architecture
of the human body sound sensor is given in Section II. The
design details of the transceiver and the sound sensor readout
circuits are presented in Section III and IV, respectively. The
experiment results is provided in Section V.
II. BODY SOUND SENSOR SYSTEM ARCHITECTURE
The wearable smart sensor for long-term body sound
recording applications consists of a body sound transducer
(miniature microphone), transceiver & sensor readout ICs, a
small antenna, a lithium ion battery and a small PCB. The
hardware is programmable with specific data processing
algorithms. Using user-friendly auxiliary shell, the sensor can
be easy for wearing.
As shown in Fig. 2, the chipset for body sound recording a
short-range wireless transceiver IC and a microphone signal
readout IC. The wireless transceiver adopts the 400MHz band
and suffers less path loss compared with BLE transceivers in
This work was supported, in part, by NSFC under contract number
61474070 and Tsinghua Internal Research Project.
Fig. 1. Typical applications of body sound monitoring
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