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The area of my research is design and development of low power and low noise analog signal conditioning integrated circuits with focus towards their application in biomedical systems. One aspect of my research is the design and development of ultra-low noise instrumentation amplifier (ULN-INA) as plug-in solution that can be used to record various bio-potentials as well as signals from bio-sensors. This fabricated INA has achieved one of the lowest Noise Efficiency Factor, as reported in literature till date. We have successfully demonstrated a complete ExG (ECG, EMG, EEG, EOG) measurement system built using our CMOS custom designed application specific integrated circuit (ASIC). Further, we have also developed a programmable gain and bandwidth INA (PGB-INA) that is highly versatile and can be used to acquire a variety of bio-potentials and sensor signals. The other aspect of my work is the development of an ultra-low power (< 200 μW) pulse oximeter (PO) ASIC suitable for application in wearable platforms with tolerance to the unavoidable finger movements. To demonstrate the functionality of the custom designed PO ASIC, we have made a fully functional pulse oximeter prototype, OxiSense. By virtue of its novel signal processing algorithm, the PPGs acquired by OxiSense is relatively immune to minor motion artefacts like shivering and finger movements which are unavoidable in many patients.

This research was funded by Ministry of Electronics and Information Technology(MeitY), Govt. of India and was carried out in the Department of Electrical Engineering, IIT Bombay with my research guide Prof. Maryam Shojaei Baghini. All the designs are silicon proven which have been fabricated in UMC 180nm mixed-mode CMOS technology by the Europractise-IC fabrication service (mini@sic) of IMEC.

Publications:
  1. D.M.Das, A. Gupta, A. Vidwans, A. Srivastava, M. Ahmad, A. Shelke, S. Kale, J. Ananthapadmanabhan, D. K. Sharma and M. Shojaei Baghini, "A Pulse Oximeter System, OxiSense, with Embedded Signal Processing using an Ultra-low Power ASIC Designed for Testability", Elsevier Microelectronics Journal, December 2017.
  2. D.M.Das, A.Srivastava, Ananthapadmanabhan J., M.Ahmad and M.Shojaei Baghini, "A novel low-noise fully differential CMOS instrumentation amplifier with 1.88 noise efficiency factor for biomedical and sensor applications", Elsevier Microelectronics Journal, July 2016. (One of the most downloaded papers in 2016)
  3. A. Srivastava, D.M.Das, P. Mathur, D. K. Sharma and M. Shojaei Baghini, "0.43 nJ/bit OOK Transmitter for Wearable and Implantable Devices in 400 MHz MedRadio Band", IEEE Microwave and Wireless Components Letters, 2018.
  4. A. Srivastava, N. Sankar K., B. Chatterjee, D.M.Das, M. Ahmad, Rakesh K. K., V. Saraf, J. Ananthapadmanabhan, D. K. Sharma, and M. Shojaei Baghini, "Bio-WiTel: A Low Power Integrated Wireless Telemetry System for Healthcare Applications in 401-406 MHz Band of MedRadio Spectrum", IEEE Journal of Biomedical and Health Informatics,December 2016.
  5. B. Chatterjee, N. Modak, Anvesha A, D. Mistry, D.M.Das and M. Shojaei Baghini, "A sub-1V, 120 nW, PVT-variation Tolerant, Tunable and Scalable Voltage Reference with 60 dB PSNA", IEEE Transactions on Nanotechnology, January 2017.
  6. D.M.Das, A. Srivastava, A. Gupta, K. Barot and M. Shojaei Baghini, "A Noise-power-area Optimized Novel Programmable Gain and Bandwidth Instrumentation Amplifier for Biomedical Applications", Proc. of IEEE ISCAS, 2017, USA.
  7. D.M.Das, J. Anantha and M.Shojaei Baghini, "Design Considerations for High-CMRR Low- Power Current Mode Instrumentation Amplifier for Biomedical Data Acquisition Systems", Proc. of IEEE ICECS, 2014, France.
  8. S. Boyapati, D.M.Das, M. Shojaei Baghini and J. M. Redoute, "A Balanced CMOS OpAmp with High EMI Immunity", Proc. of IEEE EMC Europe, 2014, Sweden.
  9. A. Srivastava, N. Sankar, D.M.Das and M. Shojaei Baghini, "LNA-LO Co-Design Considerations For Low Intermediate Frequency Receivers In 401-406 MHz MedRadio Spectrum For Healthcare Applications", International Conf. on VLSI Design, 2017, India.
  10. A. Srivastava, D.M.Das, Vignesh M S, Bharadwaj K., Sourya Dewan and Maryam Shojaei Baghini, "Bio-Telemetry And Bio-Instrumentation Technologies For Health Care Monitoring Systems", IEEE Humanitarian Technology Conf. (HTC), 2016, India.
  11. A.Srivastava, D.M.Das, D.K.Sharma and M.Shojaei Baghini, "SAW Resonator Oscillator Based Injection Locked OOK Transmitter for MedRadio Spectrum" in IEEE NEWCAS, Canada, Jun. 2016.
  12. P.Kimtee, D.M.Das and M.Shojaei Baghini, "A Mismatch Insensitive Reconfigurable Discrete Time Biosignal Conditioning Circuit in 180 nm MM CMOS Technology" in IEEE VDAT, India, May 2016.
  13. A. Srivastava, N. Sankar K, Rakesh K K, B. Chatterjee, D.M.Das and M. Shojaei Baghini, "Design And Measurement Techniques For A Low Noise Amplifier In A Receiver Chain For MedRadio Spectrum" in IEEE VDAT, India, May 2016.
Patents:
  1. Inventor in a patent filed on Ultra low noise instrumentation amplifier. Patent pending.
  2. Co-inventor in a patent filed on handheld pulse oximeter recording and analysis system. Patent pending.
  3. Co-inventor in a patent filed on a novel method for comparator input offset compensation. Patent pending.
  4. Co-inventor in a patent filed on a design method for low-power low-noise bio-medical signal conditioning circuit with extracted noise and mis-match parameters. Patent pending.
  5. Co-inventor in a patent filed on voltage mode log domain low-pass filter. Patent pending.
  6. Co-inventor in a patent filed on SAW resonator oscillator based injection locked OOK transmitter for health care applications in MedRadio spectrum (401-406 MHz). Patent pending.
  7. Co-inventor in a patent filed on design considerations for transmitter and receiver for personal health care applications. Patent pending.
Chip micrographs and layouts: