Date of Defense
28-4-2026 11:00 AM
Location
F1-1164
Document Type
Dissertation Defense
Degree Name
Doctor of Philosophy in Electrical Engineering
College
COE
Department
Electrical and Communication Engineering
First Advisor
Dr. Mohamed Atef Elsayed Abdelaal
Keywords
Photoplethysmography, PPG sensor module, optical receiver, analog front end, tansimpedance amplifier, LED dimming control, dynamic range, noise, FFT architecture.
Abstract
Photoplethysmography (PPG) sensing is an important technology used for measuring health parameters like, heart rate, respiratory rate, blood oxygen saturation, and blood pressure (BP). The PPG sensing is used for individuals who have to periodically monitor their health due to chronic health conditions. The basic requirements of a wearable PPG sensor include non-invasiveness, prolonged battery life, and being user-friendly. These type of sensors have great demand in the healthcare applications and there is a significant rise in the demand of these sensors. The basic objective of these PPG sensors is to make the continuous vital health monitoring easier without the need for frequent medical supervision. Low power consumption and high integration are the basic specifications these PPG sensors need to meet, inorder to match the needs of modern healthcare.
This thesis introduces a novel design of a PPG sensor with a transimpedance amplifier (TIA). A Direct Current (DC) compensation loop is incorporated in the TIA. This circuit provides high gain, low noise, and minimized power consumption. The system also improves the dynamic range (DR). The DC compensation loop incorporated in the circuit reduces the noise at low PPG signal levels. This helps the circuit in enhancing system performance. The DC compensation loop maintains the signal integrity even at higher PPG signal levels. This helps the system in removing the DC components effectively. The system also introduces an automatic light control (ALC) module. The incorporation of this module eliminates the need for an analog-to-digital converter (ADC). The ALC has the ability to reduce the LED driving current especially during high PPG signal levels. This helps the system minimize the power consumption and also extend the dynamic range of the PPG sensory system.
Secondly, the thesis introduces a capacitive feedback common drain feedback transimpedance amplifier (CF-CDF-TIA) into the PPG sensory system. This CF-CDF-TIA helps the PPG sensor system maintain a balance between power efficiency and noise reduction. The CF-CDF-TIA introduced in the PPG sensor, helps the PPG sensor achieve high sensitivity. The CF-CDF-TIA also integrates an ALC module into the circuit. This inclusion helps the circuit manage the LED current levels and hence maintain the signal quality. This means that the ALC can reduce the LED current when the input photocurrent is high. This helps in improving the overall system performance. All these features makes the sensor suitable for high dynamic range, wearable, health monitoring applications.
Thirdly, the output from the integrated PPG sensor is fed into a Fast Fourier Transform (FFT) to extract Heart Rate (HR). A single-Path Delay Commutator Processing Element (SDC-PE) is incorporated in the FFT design. The SDC-PE helps in optimizing the hardware utilized by reducing the number of adders and other memory modules to a much lesser number compared to that used in traditional FFT designs. This factor helps in enhancing the efficiency of pipelined FFT operations.
Included in
A LOW-NOISE AND HIGH-GAIN INTEGRATED PHOTOPLETHYSMOGRAPHY SENSOR FOR CONTINUOUS VITAL SIGNS MONITORING
F1-1164
Photoplethysmography (PPG) sensing is an important technology used for measuring health parameters like, heart rate, respiratory rate, blood oxygen saturation, and blood pressure (BP). The PPG sensing is used for individuals who have to periodically monitor their health due to chronic health conditions. The basic requirements of a wearable PPG sensor include non-invasiveness, prolonged battery life, and being user-friendly. These type of sensors have great demand in the healthcare applications and there is a significant rise in the demand of these sensors. The basic objective of these PPG sensors is to make the continuous vital health monitoring easier without the need for frequent medical supervision. Low power consumption and high integration are the basic specifications these PPG sensors need to meet, inorder to match the needs of modern healthcare.
This thesis introduces a novel design of a PPG sensor with a transimpedance amplifier (TIA). A Direct Current (DC) compensation loop is incorporated in the TIA. This circuit provides high gain, low noise, and minimized power consumption. The system also improves the dynamic range (DR). The DC compensation loop incorporated in the circuit reduces the noise at low PPG signal levels. This helps the circuit in enhancing system performance. The DC compensation loop maintains the signal integrity even at higher PPG signal levels. This helps the system in removing the DC components effectively. The system also introduces an automatic light control (ALC) module. The incorporation of this module eliminates the need for an analog-to-digital converter (ADC). The ALC has the ability to reduce the LED driving current especially during high PPG signal levels. This helps the system minimize the power consumption and also extend the dynamic range of the PPG sensory system.
Secondly, the thesis introduces a capacitive feedback common drain feedback transimpedance amplifier (CF-CDF-TIA) into the PPG sensory system. This CF-CDF-TIA helps the PPG sensor system maintain a balance between power efficiency and noise reduction. The CF-CDF-TIA introduced in the PPG sensor, helps the PPG sensor achieve high sensitivity. The CF-CDF-TIA also integrates an ALC module into the circuit. This inclusion helps the circuit manage the LED current levels and hence maintain the signal quality. This means that the ALC can reduce the LED current when the input photocurrent is high. This helps in improving the overall system performance. All these features makes the sensor suitable for high dynamic range, wearable, health monitoring applications.
Thirdly, the output from the integrated PPG sensor is fed into a Fast Fourier Transform (FFT) to extract Heart Rate (HR). A single-Path Delay Commutator Processing Element (SDC-PE) is incorporated in the FFT design. The SDC-PE helps in optimizing the hardware utilized by reducing the number of adders and other memory modules to a much lesser number compared to that used in traditional FFT designs. This factor helps in enhancing the efficiency of pipelined FFT operations.