Low-power low-noise analog signal conditioning chip with on-chip drivers for healthcare applications

This paper presents an ultra low-noise, low-voltage complete analog signal conditioning chip, fabricated in 180nm mixed-mode CMOS process. In contrast to many already-reported biomedical chips the test chip has been fabricated in a relatively scaled technology operating at low supply voltage of 1.8V. This enables targeting energy-efficient hand-held biomedical devices where low-noise analog signal conditioning, preliminary processing and low-power wireless functionalities will be integrated on one chip. The test chip features instrumentation amplifier (INA) with chopper modulation at the first stage. The second stage is a novel area efficient spike removal filter (SRF) for attenuating coupled chopping spikes. The last stage is a differential active RC filter to adjust gain and bandwidth of the forward channel. On-chip non-overlapping clock generators with frequency of 4kHz and 8kHz for SRF stage are also implemented on the test. The chip also features a reconfigurable driven-right-leg circuit (DRLC) and shield drive amplifier (SDA) in the feedback path specifically for portable healthcare instruments. The DRLC provides the feedback either with operational amplifier (op-amp) or operational transconductance amplifier (OTA), configurable by the user. The presented test chip, for the first time, demonstrates an integrated OTA-based DRLC along with INA. INA and drivers have been designed and optimized for minimum power dissipation using a power-oriented design flow. The measurement results show that the INA achieves input-referred noise density of 28nv/Hz and DC current of [email protected] maintaining minimum of 109dB at 1.91kHz. Measurements also show that 34dB interference reduction at 50Hz is achieved with DRLC. Low operating voltage, wide range of specifications and reconfigurable modules and interconnections enable the chip to be used for broad range of signal conditioning applications.

[1]  P. Mathys,et al.  Reduction of power line interference using active electrodes and a driven-right-leg circuit in electroencephalographic recording with a minimum number of electrodes , 2004, The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[2]  R. Jacob Baker,et al.  CMOS Circuit Design, Layout, and Simulation, Second Edition , 2004 .

[3]  Refet Firat Yazicioglu,et al.  Ultra-low power biopotential interfaces and their application in wearable and implantable systems , 2007 .

[4]  M. Shojaei-Baghini,et al.  A Low-Power and Compact Analog CMOS Processing Chip for Portable ECG Recorders , 2005, 2005 IEEE Asian Solid-State Circuits Conference.

[5]  Refet Firat Yazicioglu,et al.  Biopotential Acquisition Systems , 2006 .

[6]  John G. Webster,et al.  Driven-right-leg circuit design , 1983, IEEE Transactions on Biomedical Engineering.

[7]  Refet Firat Yazicioglu,et al.  A 60 $\mu$W 60 nV/$\surd$Hz Readout Front-End for Portable Biopotential Acquisition Systems , 2007, IEEE Journal of Solid-State Circuits.

[8]  Refet Firat Yazicioglu,et al.  A 30µW Analog Signal Processor ASIC for biomedical signal monitoring , 2010, 2010 IEEE International Solid-State Circuits Conference - (ISSCC).

[9]  Refet Firat Yazicioglu,et al.  Ultra-low power biopotential interfaces and their application in wearable and implantable systems , 2007, 2007 2nd International Workshop on Advances in Sensors and Interface.

[10]  R. Jacob Baker,et al.  CMOS Circuit Design, Layout, and Simulation , 1997 .

[11]  Qiuting Huang,et al.  A fully integrated, untrimmed CMOS instrumentation amplifier with submicrovolt offset , 1999 .

[12]  A.-T. Avestruz,et al.  A 2 $\mu\hbox{W}$ 100 nV/rtHz Chopper-Stabilized Instrumentation Amplifier for Chronic Measurement of Neural Field Potentials , 2007, IEEE Journal of Solid-State Circuits.

[13]  E.M. Spinelli,et al.  A transconductance driven-right-leg circuit , 1999, IEEE Transactions on Biomedical Engineering.

[14]  J G Webster,et al.  60-HZ interference in electrocardiography. , 1973, IEEE transactions on bio-medical engineering.

[15]  Ron Hogervorst,et al.  A compact power-efficient 3 V CMOS rail-to-rail input/output operational amplifier for VLSI cell libraries , 1994 .

[16]  C A Grimbergen,et al.  High-quality recording of bioelectric events , 1991, Medical and Biological Engineering and Computing.

[17]  Refet Firat Yazicioglu,et al.  A 30 $\mu$ W Analog Signal Processor ASIC for Portable Biopotential Signal Monitoring , 2011, IEEE Journal of Solid-State Circuits.

[18]  Yuan-Ting Zhang,et al.  An ECG measurement IC using driven-right-leg circuit , 2006, 2006 IEEE International Symposium on Circuits and Systems.

[19]  John G. Webster,et al.  Medical Instrumentation: Application and Design , 1997 .

[20]  Maryam Shojaei Baghini,et al.  An Ultra-Low-Power Current-Mode Integrated CMOS Instrumentation amplifier for Personal ECG Recorders , 2008, J. Circuits Syst. Comput..

[21]  Feng Wan,et al.  A 90nm CMOS bio-potential signal readout front-end with improved powerline interference rejection , 2009, 2009 IEEE International Symposium on Circuits and Systems.

[22]  C. A. Grimbergen,et al.  HIGH QUALITY RECORDING OF BIOELECTRIC EVENTS . I : INTERFERENCE REDUCTION , THEORY AND PRACTICE , 2009 .