Introduction

The PPG6350 -- Pulse Oximeter Based Heart Rate Monitor chip is an integrated circuit chip designed and tested by Xiaowen Han and Muqing Liu for the course EE6350 - VLSI Design Lab taught by Prof. Peter Kinget at the Columbia University Electrical Engineering Department in spring 2014.

The goal of this course is to develop the main skills of IC design, as well as expose the students to practical aspects of this process. Under supervision, students were required to do all the steps of the chip development process: defining the application and specifications of the IC, system and transistor level simulations, layout, parasitic extraction and post-layout simulations, tape-out to the foundry, and finally experimental verifications on the fabricated IC. The chip fabrication was donated by MOSIS under their educational program.

The pulse oximeter based heart rate monitor chip is designed to detect the heart rate. The chip can monitor the heart rate using Photophlethysmogram (PPG) technique as shown in the figure below, which is a non-invasive method to detect the change in blood volume that is periodic since it is caused by the heartbeat. In this project, the chip detects the PPG signal from the fingertip. The signal the heart rate monitor chip is dealing with is caused by the change of light absorption through the skin. The DC component of the signal indicates the bulk absorption of the skin tissue, and the AC component indicates the variation in blood volume in the skin caused by the pressure pulse of the cardiac cycle.[1]

PPG_introduction
Fig. 1 - Principle of Photophlethysmogram (PPG)


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