Analog Signal Chain considerations for Medical applications. Bio-Potential signals (ECG/EEG)

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1 Analog Signal Chain considerations for Medical applications Bio-Potential signals (ECG/EEG)

Bio-potential signals Types of bio-potential signals & other related measurements Electro-Cardiogram Signal chain ECG Lead Derivation Input Filtering and Defibrillation Protection Typical ECG System

2 Bio-potential signals Types of bio-potential signals & other related measurements Electro-Cardiogram Signal chain ECG Lead Derivation Input Filtering and Defibrillation Protection Typical ECG System Block Diagram The INA front end Right Leg Drive (RLD) Amplifier Selection and Design The ECG Shield Drive Lead Off Detection PACE Detection Gain, Resolution and Filtering ADS129x Introduction, Features, and Advantages Lowest power LMP9050x introduction Questions

3 Types of bio-potential signals & Common measurements EEG (ElectroEncephaloGraphy) electrical activity of the brain ECG (ElectroCardioGraphy) electrical activity of the heart EMG (ElectroMyoGraphy) electrical activity by skeletal muscles Pace signal Signal from Pacemaker Respiration study of impedance created from inhale/exhale

4 What is Electrocardiogram (ECG)? A measure of the electrical activity of the heart

What is ElectroEncephaloGraphy (EEG)? Electroencephalography (EEG) is the recording of electrical activity along the scalp, produced by the firing of neurons within the brain.

[ Other uses for EEG include: Bi-spectral index (BIS) monitor is a neuro-physiological monitoring device which continually analyses a patient's electroencephalograms during general anesthesia to

5 What is ElectroEncephaloGraphy (EEG)? Electroencephalography (EEG) is the recording of electrical activity along the scalp, produced by the firing of neurons within the brain. In neurology, the main diagnostic application of EEG is in the case of Epilepsy, as epileptic activity can create clear abnormalities on a standard EEG study. [ Other uses for EEG include: Bi-spectral index (BIS) monitor is a neuro-physiological monitoring device which continually analyses a patient's electroencephalograms during general anesthesia to assess the level of consciousness during anesthesia Evoked Potentials(EP) - EP involves averaging the EEG activity timelocked to the presentation of a stimulus of some sort (visual, somatosensory, or auditory). Event-Related Potentials (ERPs) - Refers to averaged EEG responses that are time-locked to more complex processing of stimuli. Traumatic Brain Injury (TBI) Software algorithms have been developed that can accurately determine the presence of damaged brain tissue. Stroke Detection Software algorithms have been developed that can accurately determine Stroke occurrence.

recording the electrical activity produced by muscles.

electromyograph, to produce a record called an

potential generated by muscle cells when these cells are

The signals can be analyzed to detect medical abnormalities,

biomechanics of human or animal movement.

6 What is ElectroMyoGraphy (EMG)? Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by muscles. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram An electromyograph detects the electrical potential generated by muscle cells when these cells are electrically or neurologically activated. The signals can be analyzed to detect medical abnormalities, activation level, recruitment order or to analyze the biomechanics of human or animal movement. These electrical pulses can be detected on the surface(on the skin with electrodes) Frequently needle electrodes are used to penetrate the muscle directly for measurement.

7 Bandwidth of interest

8 ECG/EEG/EMG Signal Characteristics Electrode offset /- 300mV signal signal ECG : < /- 2.5mV EEG : /- 10uV to 100uV EMG : /-50uV to 30mV ECG : Hz EEG : Hz EMG : 7Hz 20Hz Common mode 50 / 60Hz 1.5V 0V Noise specification over the specified bandwidth ECG : 10uVpk-pk EEG : 1uVpk-pk EMG : 5uVpk-pk

9 Typical ECG plot? Actual ECG-normal

10 ECG Measurement reality? ECG irregular tracings due to external artifacts

11 Skin Electrode Interface Model Electrical characteristics include a DYNAMIC resistance, capacitance, and offset voltage

12 Bio-potential signals Types of bio-potential signals & Common measurements Electro-Cardiogram analog signal chain ECG Lead Derivation Typical ECG System Block Diagram Input Filtering and Defibrillation Protection The INA front end Right Leg Drive (RLD) Amplifier Selection and Design The ECG Shield Drive Lead Off Detection PACE Detection Gain, Resolution and Filtering ADS129x Introduction, Features, and Advantages Lowest power LMP9050x introduction Questions

13 ECG Lead Derivation ECG Einthoven Triangle, Body Electrodes, 3 Derived Leads = I, II, III LEAD I = V LA-RL V RA-RL LEAD II = V LL-RL V RA-RL LEAD III = V LL-RL V LA-RL Einthoven s Law Right Leg Reference, RL In electrocardiogram at any given instant the potential of any wave in Lead II is equal to the sum of the potentials in Lead I and III.

14 Standard Lead Configurations Standards Electrodes Needed 1 Lead LA, RA 3 Lead LA, RA, LL 6 Leads LA, RA, LL 12 Leads LA, RA, LL, V1-6

15 Typical 8-Channel ECG System Solution Cost ~ $30 - $50 PWB ~ 1,845mm 2 Power ~ 200mW Components ~ 44 15

filter1 R filter2 RA NE2H R Patient R filter1 C F R filter2 C CM C diff -V s V s Zener Diode NE2H C F C

16 ECG Input Filtering and Protection Example: LEAD I Protection with Input Filtering Series Resistance Limits Input Current C F, C cm, and C diff R filter form LPF Protection Diodes V s LA R Patient R filter1 R filter2 RA NE2H R Patient R filter1 C F R filter2 C CM C diff -V s V s Zener Diode NE2H C F C CM -V s Patient Protection 10-20k ohms Ne2H Lamps/TVS Protect Against Defibrillation Voltages C diff = 10 x C cm

17 The INA Front End Key Features of the INA Front End

18 The INA Front End Ideal Simulation Circuit with Current and Voltage Noise Sources C12 33p C19 33p C20 330p C18 33p C10 33p nv ECG Skin Impedance C6 100p Electrode Impedance Offset C7 47n Input CM Differential Filtering Ideal INA Front End R21 1k R19 1k V4 0 R1 63.4k R3 63.4k Vn12 Vnoise ECGp R14 100k R20 1k Vout Vref C8 100p R23 1k C9 47n V5 0 R4 63.4k R5 63.4k - - INA 1 Vref R25 1k R22 100k R24 1k fa In12 In_fA

50/60Hz noise *Tapping off center of split gain resistor feeds the following

19 The RL Drive Amplifier The RL Drive Amplifier Serves 2 Purposes: (1) Common Mode Bias (2) Noise Cancellation Average VCM is Inverted and Fed Back to RL; Cancels 50/60Hz noise *Tapping off center of split gain resistor feeds the following voltage to the RL Drive Circuit [(V cm ECG P ) (V cm ECG n )]/ 2 = V cm (ECG p ECG n )/2

20 The ECG Shield Drive Shield drive eliminates leakage to ECG Inputs ECG P C P1 ECG N V CC /2 C P2 Shield is driven to (V IN() V IN( ) ) /2 Eliminates Leakage from C P1 and C P2 Capacitance of cable can be 500 pf to 1.5 nf Isolation resistor Necessary for improved EMI/RFI filtering

21 Lead Off Detection Lead Off Differentiates a Bad Lead from an Arrhythmia Body-Electrode Model V CC V TH V REF V TH Pull up Resistors Force IN to Comparator High When Lead is Removed Comparator Voltage triggers ALERT Lead Off Indicative of Weak Lead

22 Pace Detect Pace Maker Pulse Specifications d p a p t 0 a o a p = Amplitude (2-700mV) a o = Overshoot d p = Pulse Width (0.1 to 2mS) t 0 = Overshoot Time Constant (4-100ms)

R23 1M R22 1M R8 400k 100k R7 2M 33p 10k R17 1M R3 1M C9 330p R1 100k 10k 33p R6 2M R5 2M Hadware Pace Detection Pace Detect Circuitry in Parallel with ECG Signal Path VCC Vpace Pos 47n ECGp 52k ECGn

23 R23 1M R22 1M R8 400k 100k R7 2M 33p 10k R17 1M R3 1M C9 330p R1 100k 10k 33p R6 2M R5 2M Hadware Pace Detection Pace Detect Circuitry in Parallel with ECG Signal Path VCC Vpace Pos 47n ECGp 52k ECGn 47n Vpace Neg 52k 10n R20 100k U7 OPA348 - VCC Vref 63.4k 63.4k R18 10k - - U6 OPA348 VCC VCC RG V RG V- Vref Vout Ref Out U5 INA333 - VCC 10n OPA348 VECG_block R2 1k OPA348 Vref - R4 100k C2 100p VCC AC Coupled Input Blocks ECG Signal and Retains the PACER Pulse Window Comparator Triggers if PACER Signal Detected Separate PACER Processing Circuitry VCC VCC TLV3701 Vpace1 - VPDetect - - VCC Vpace2 - TLV3701

24 Gain, Resolution and Filtering Choice of High Gain SAR ADC OR Low Gain 24 bit Delta Sigma ADC At electrode High Gain with low noise amplifiers At ADC At At electrode Low gain At At ADC Amplitude x200 Noise free Dynamic range Amplitude Amplitude x5 Noise free Dynamic range ADC Amp Noise noise Signal Chain Signal Chain a) Using a low resolution ADC b) Using a high resolution ADC SAR filter Option Results in Same Input-Referred Noise as the DC Coupled Delta-Sigma, but at what COST?

Gain, Resolution and Filtering Comparison of Delta Sigma ADC vs. Lower Resolution SAR ADC Using a low resolution ADC x5 0.

25 Gain, Resolution and Filtering Comparison of Delta Sigma ADC vs. Lower Resolution SAR ADC Using a low resolution ADC x Hz x Hz Elec 1 Elec 2 INA Elec 8 Patient Protection, Lead selection INA DC blocking HPF Additional gain High order Anti aliasing filter MUX ADC 16 bit, 100KSps ` DOUT Elec 9 RL Using a high resolution ADC Elec 1 Elec 2 Elec 8 Elec 9 Patient Protection, Lead selection x5 INA INA 100 Hz Simple RC filter MUX ADS1258 ADC 24 bit, 100KSps ` DOUT Reduced Hardware Filter Requirements Relaxed Lower Power Lower System Cost Electrode Offset Info Retained RL

26 Gain, Resolution and Filtering Block Diagram of INA Gain, Simple RC Filter, and ADS1298 x5 x5 x Hz Hz 100 Hz Elec Elec 1 1 Elec Elec 2 2 Elec 1 90 Elec 2 INA INA INA ADC ADS1258 ADS1258 DOUT1 24 bit,2ksps Patient Patient Protection, Protection, Lead Lead Lead selection selection Simple RC RC filter Simple filter RC filter MUX ` MUX ADC DOUT ADC DOUT Elec Elec 8 8 Elec 8 INA INA INA ADC 24 bit, 24 bit, DOUT8 100KSps 100KSps ` ` Elec Elec 9 9 Elec 9 24 bit,2ksps RL RL RL ` A single ADC in the MUX approach does not necessarily mean lower power due to the higher speed needed to perform MUX switching

27 Bio-potential signals Types of bio-potential signals & and other related measurements Electro-Cardiogram Signal chain ECG Lead Derivation Input Filtering and Defibrillation Protection Typical ECG System Block Diagram The INA front end Right Leg Drive (RLD) Amplifier Selection and Design The ECG Shield Drive Lead Off Detection PACE Detection Gain, Resolution and Filtering ADS129x Introduction, Features, and Advantages

Control and SPI Input Mux 28 ADS1298 Integrated

Protection L(LA) 16-24bit IA ADC F(LL) 51% Lower Cost

ADS1298 16-24bit ADC BT Amp RTC 95% C3(V3) Less PWB

Less Power 16-24bit IA C6(V6) ADC 16-24bit IA ADC 95%

Monitor Charge r PSU Disp Lamp C / DSP TMS320F28xx

28 Control and SPI Input Mux 28 ADS1298 Integrated 8-Channel ECG System Solution R(RA) Patient Protection L(LA) 16-24bit IA ADC F(LL) 51% Lower Cost 16-24bit IA C1(V1) ADC 16-24bit C2(V2) IA ADC IA ADS bit ADC BT Amp RTC 95% C3(V3) Less PWB 16-24bit IA ADC C4(V4) 16-24bit IA ADC C5(V5) 95% Less Power 16-24bit IA C6(V6) ADC 16-24bit IA ADC 95% Less Parts Lead Off Calibration Temp PACE DETECT Ref Monitor Charge r PSU Disp Lamp C / DSP TMS320F28xx TMS320C5000 SD CF USB RS23 2 BUTTON I/F RLD Protect WCT WILSON Amp RESPIRATION

ADS1x9xR Available Options 4, 6, and 8 Channel, 16 & 24-bit Key Features Provides

Noise: 4uV p-p* (150Hz BW, G=6) CMRR : 105dB ** with G = 6 Crosstalk : -105dB High

2mW/Channel Low Power Mode: 750μW/Channel Data Rates: 250SPS to 32000SPS

5V Built in test signals Built in RLD amp Continuous Lead Off detect option Built

29 ADS1x9xR Available Options 4, 6, and 8 Channel, 16 & 24-bit Key Features Provides 3-Lead, 6-Lead & 12-Lead ECG 4/6/8 low noise Amplifiers 4/6/8 high resolution ADCs Noise: 4uV p-p* (150Hz BW, G=6) CMRR : 105dB ** with G = 6 Crosstalk : -105dB High Resolution Mode: 1.2mW/Channel Low Power Mode: 750μW/Channel Data Rates: 250SPS to 32000SPS Programmable Gain (1,2,3,4,6,8,12) 2.9 5V / V supplies & Bi-Polar ± 2.5V Built in test signals Built in RLD amp Continuous Lead Off detect option Built in oscillator Pace Detect Channel Select (HW / SW) Respiration Impedance (ADS129xR Only) Internal / External Reference Flexible Power Down, STBY mode SPI Data Interface 29

30 The ADS1x94/6/8R The All-In-One ECG Chip

31 VCAP3P VREFP VREFN VBG VCAP4P The ADS1x91/2/R The All-In-One ECG Chip RESPP/IN3P RESPN/IN4P/IN3N IN2P IN2N IN1P IN1N RLD_IN/RLD_REF RLD_INV RLD_OUT Test RESP MOD MUX RFI Temp Sensor Lead-Off Current Source. A2 A1 - REF RESP DEMOD VCAP3N VCAP4N Reference ADC2 ADC1 AVDD Programmable AVSS /PWDN /RESET Control DVDD SPI Osc. DGND /DRDY /CS SCLK DIN DOUT CLKSEL CLK IN/OUT START GPIO1/RCLKOP GPIO2/RCLKOPH VCAP

32 The ADS1x9x Device Versions The All-In-One bio-potential Family

33 ADS1298, ADS1296, ADS1294 Competition ADS129x ADS119x National Aurelia-Cardiac ASIC IMEC Maxim Freescale Analog Devices High performance, 24-bit integrated complete ECG Analog Front End. High value, 16-bit integrated complete ECG Analog Front End. Previewing single channel device with integrated PGA and 16-bit ADC This is not single chip solution. It is an integrated module with lots of passives necessary. Academic design with potential to find industrial partner to bring a competing product to market. Rumored to be working on an integrated solution. Has shown block diagram to customers, but has not produced working device. Advertising ECG-on-a-chip based on MCU system with poor analog performance. Rumored to be working on integrated solution, but currently marketing high-performance discrete solution. Feature or Specification Critical for ADS129x IMEC Aurelia ADI AED/Telemedicine Patient Monitor/ ECG EEG Sports & Fitness/ Gaming/Home Noise (μv pk-pk ) X X (Discrete Solution) CMRR (db) X X X X Dynamic Range X X ±1 ±50 ±300 Wide (mv) # Channels X X 8, 6, Pace Detect X Y N Y N Respiration X Y N Y N Leadoff Detect X X X X Y N N N Power per Ch X X (mw) Package (pins) X X X N/A Size (mm x mm) X X X 8 x 8 N/A 14 x 14 N/A Cost ($/ch) X X $2.99 N/A $12.5 N/A

34 TI s ADS129x vs. ADI s new ADAS1000

35 Executive Summary TI significantly outperforms ADI in integration, power and noise. TI has a portfolio of pin-compatible devices that are released and in production. Multiple customers have successfully designed with us. ADI has a single device in preview status on the web TI clearly leads in ADCs for ECG and the factory team is committed to helping the field continue to win in this space.

36 TI vs. ADI at a glance Feature TI ADS1294/6/8 ADI ADAS1000 # of channels 4, 6 or 8 Only 5 Power / channel (mw) Noise (µv p-p) List Price More than 5x lower! 4 More than 2x lower! $12 (4 channels) $18 (6 channels) $24 (8 channels) 3.8 to $28 (5 channels) Status Product Release Pre-release

37 Channel Count: Advantage TI TI has 4, 6 or 8 channel options ADI has only a 5 channel device Impact to Customer: The TI solution supports a 12 lead implementation in a single package. Two ADI chips are required for a standard 12 lead ECG.

38 Power Consumption: Advantage TI TI: mW/channel mW/channel 4 1.0mW/channel ADI: 5 3.8mW/channel 3 4.7mW/channel Impact to Customer: Lowering power is critical as ECG systems become smaller and more portable.

39 Noise Performance: Advantage TI TI: Input Referred noise is 4 µvp-p (130HZ BW, low-power mode) ADI: Input Referred noise is 10 µvp-p (150Hz BW) Impact to Customer While ADI s higher noise may be nominally acceptable for ECG, TI s lower noise gives customers more margin in their designs, more confidence in our device and expands the applications we can serve.

40 Packaging: Advantage TI TI: 12mm x 12mm TQFP or 8mm x 8mm BGA ADI: 12mm x 12mm TQFP or 8mm x 8mm QFN Impact to Customer: Shrinking footprint is critical as ECG systems become more portable. In same footprint, TI has 8 channels to ADI s 5.

41 Solution Scalability: Advantage TI TI can address a broad range of ECG/EEG products: 3 lead ECG to 256 channel EEG. ADI s limited information only mentions 6 lead or 12 lead (12 leads would require 2 ADI devices). Impact to Customer: TI is successfully designed in a wide range of biopotential measurement systems including a 250 channel EEG analyzer. Our daisy-chainable serial interface helps minimize overhead in high channel count systems.

42 Portfolio Offering: Advantage TI The TI offers a portfolio of pin-compatible RELEASED solutions ADS1298R 24bit, 8-Channel Pace RLD Respiration ADS bit, 8-Channel Pace RLD ADS1296R 24bit, 6-Channel Pace RLD Respiration ADS bit, 6-Channel Pace RLD ADS1294R 24bit, 4-Channel Pace RLD Respiration ADS bit, 4-Channel Pace RLD ADS bit, 8-Channel Pace RLD ADS bit, 8-Channel Pace RLD ADS bit, 8-Channel Pace RLD ADI has only one PREVIEW device ADAS Channel Pace RLD Respiration

43 IEC (Monitoring) Lead Configurations ECG Standard Electrodes Needed 1 Lead LA, RA 3 Lead LA, RA, LL 6 Leads LA, RA, LL 12 Leads LA, RA, LL, V1-6 Followed by Edan, Fukuda-Densi Nihon-Koden

44 IEC (Diagnostic) Lead Configurations Standards Electrodes Needed 1 Lead LA, RA 3 Lead LA, RA, LL 6 Leads LA, RA, LL 12 Leads LA, RA, LL, V

45 Breamar Holter Lead and electrode defnitions reversed! Lead Configurations Channels? Electrodes? Leads? Each vendor Has its own Placements!

46 Philips Holter 12 leads from five electrodes! Lead Configurations Big vendors Have patented stuff. Small guys will follow Standard way. Philips patent : electrodes, All 12 leads are mathmatically derived, non-standard placement GE patent : electrodes, some leads are derived, standarad placement if electrodes Interesting Article :

47 Lead calculation & systems approaches Lead Configurations Analog computation (Differential) Digital computation (Single ended) With RLD (DC coupled) No RLD (AC coupled??) 1 Lead Analog >> 3 Lead Analog >> 6 Lead Analog >> 3/6 Lead Digital >> 3/6 Lead Respiration 7 Lead Analog >> 7 Lead Respiration A 7 Lead Digital >> 12 Lead Analog >> 12 Lead Respiration 12 Lead Analog & Digi 12 Lead Digital >> 12 Lead Respiration

48 1 Lead, 2 Electrode RLD, 1-Channel Analog Computation Lead Configurations Lead I : LA - RA = Analog KEY = Computation Digital Computation

49 3 Lead, 3 Electrode RLD, 3-Channel Analog Computation Lead Configurations Lead I : LA Lead - RA II : LL Lead - RA III : LL - LA = Analog KEY = Computation Digital Computation

50 50 6 Lead, 3 Electrode RLD, 6-Channel Analog Computation Lead Configurations LEAD I = LA - RA LEAD II = LL - RA Lead III : LL - LA avr = RA (LA LL) avl / = 2LA (RA LL) avf / = 2LL (RA LA) / 2 (RA (LA LL) / 2LL) /(RA 2 LA) / 2 Wilson = 0.333(RALALL) Ch1,2,3 : limb leads Ch 4,5,6 : internally rou = Analog KEY = Computation Digital Computation

51 3 Lead / 6 Lead, 3 Electrodes RLD, 3-Channel Digital Computation Lead Configurations Lead I : LA - Lead RA II : LL - Lead RA III : LL - LA avr : RA (LALL)/2 avl : (RALL)/2 avf : (LARA)/2 3 Leads 6 Leads = Analog KEY = Computation Digital Computation

52 3 Lead / 6 Lead, Respiration, 3 Electrodes RLD, 4-Channel Digital Computation Lead Configurations RESPIRATION Lead I : LA - Lead RA II : LL - Lead RA III : LL - LA avr : RA (LALL)/2 avl : (RALL)/2 avf : (LARA)/2 3 Leads 6 Leads = Analog KEY = Computation Digital Computation

2LA (RA LL) avf / = 2LL (RA LA) / 2 (RA (LA LL) / 2LL) /(RA 2 LA) / 2 V = V 0.

53 53 7 Lead, 4 Electrode RLD, 7-Channel Analog Computation Lead Configurations LEAD I = LA - RA LEAD II = LL - RA Lead III : LL - LA avr = RA (LA LL) avl / = 2LA (RA LL) avf / = 2LL (RA LA) / 2 (RA (LA LL) / 2LL) /(RA 2 LA) / 2 V = V 0.333(RALALL) Wilson = 0.333(RALALL) = Analog KEY = Computation Digital Computation

7 Lead Respiration, 4 Electrodes RLD, 8-Channel Analog Computation Lead Configurations RESPIRATION LEAD I = LA - RA LEAD II = LL - RA Lead III : LL - LA avr = RA (LA LL) avl / = 2LA (RA LL) avf / =

54 7 Lead Respiration, 4 Electrodes RLD, 8-Channel Analog Computation Lead Configurations RESPIRATION LEAD I = LA - RA LEAD II = LL - RA Lead III : LL - LA avr = RA (LA LL) avl / = 2LA (RA LL) avf / = 2LL (RA LA) / 2 (RA (LA LL) / 2LL) /(RA 2 LA) / 2 V = V 0.333(RALALL) Wilson = Ch1 : respiration 0.333(RALALL) Ch2,3,4 : limb le Ch 5,6,7 : interna = Ch Analog KEY 8 : V lead = Computation Digital Computation

55 7 Lead, 3 Electrodes RLD, 3-Channel Digital Computation Lead Configurations Lead I : LA - Lead RA II : LL - Lead RA III : LL - LA avr : RA (LALL)/2 avl : (RALL)/2 avf : (LARA)/2 V1 = V1 - (LA RA LL)/3 3 Leads 6 Leads 7 Leads = Analog KEY = Computation Digital Computation

12 Lead, 9 Electrode RLD, 12-Channel Analog Computation Lead Configurations LEAD I = LA - RA LEAD II = LL - RA Lead III : LL - LA avr = RA (LA LL) avl / = 2LA (RA LL) avf / = 2LL (RA LA) / 2 (RA (LA

56 12 Lead, 9 Electrode RLD, 12-Channel Analog Computation Lead Configurations LEAD I = LA - RA LEAD II = LL - RA Lead III : LL - LA avr = RA (LA LL) avl / = 2LA (RA LL) avf / = 2LL (RA LA) / 2 (RA (LA LL) / 2LL) /(RA 2 LA) / 2 Wilson = 0.333(RALALL) V1 = V1 - (LA V2 LL)/3 = V2 - (LA RA V3 LL)/3 = V3 - (LA RA V4 LL)/3 = V4 - (LA RA V5 LL)/3 = V5 - (LA RA V6 LL)/3 = V6 - (LA RA LL)/3 = Analog KEY = Computation Digital Computation

57 12 Lead Respiration, 9 Electrode RLD, 13-Channel Analog Computation Lead Configurations RESPIRATION LEAD I = LA - RA LEAD II = LL - RA Lead III : LL - LA avr = RA (LA LL) avl / = 2LA (RA LL) avf / = 2LL (RA LA) / 2 (RA (LA LL) / 2LL) /(RA 2 LA) / 2 Wilson = 0.333(RALALL) V1 = V1 - (LA V2 LL)/3 = V2 - (LA RA V3 LL)/3 = V3 - (LA RA V4 LL)/3 = V4 - (LA RA V5 LL)/3 = V5 - (LA RA V6 LL)/3 = V6 - (LA RA LL)/3 = Analog KEY = Computation Digital Computation

58 58 12 Lead, 9 Electrode RLD, 8-Channel Combined Analog & Digital Computation Lead Configurations LEAD I = LA - RA LEAD II = LL - RA LEAD III = LEAD I - LEAD II avr = RA = (LA-RA) (LA (LL-RA) = LA - LL LL) / 2 = -(LEAD1 LEAD2)/2 avl = LA (RA = -(LALL-2RA)/2 = RA (LALL)/2 LL) / 2 =-(LEAD3 LEAD1)/2 = -(LEAD1-LEAD2LA-RA)/2 avf = LL (RA = -(LA-LLLA-RA)/2 = LA (RALL)/2 LA) / 2 =(-LEAD3 LEAD2)/2 V1 = (-(LEAD1-LEAD2)LL-RA)/2 V1 - (LA RA (LL-LALL-RA)/2 V2 LL)/3 = V2 (RALA)/2 - (LA RA V3 LL)/3 = V3 - (LA RA V4 LL)/3 = V4 - (LA RA V5 LL)/3 = V5 - (LA RA V6 LL)/3 = V6 - (LA RA Wilson LL)/3= 0.333(RALALL) = Analog KEY Computation = Digital Computation

59 12 Lead, 9 Electrode RLD, 9-Channel Digital Computation Lead Configurations Wilson = LEAD (RALALL)/3 I = - RA LEAD II = LL - RA LEAD III = LL - LA avr = RA (LA LL) avl / = 2LA (RA LL) avf / =

59 59 12 Lead, 9 Electrode RLD, 9-Channel Digital Computation Lead Configurations Wilson = LEAD (RALALL)/3 I = - RA LEAD II = LL - RA LEAD III = LL - LA avr = RA (LA LL) avl / = 2LA (RA LL) avf / = 2LL (RA LA) V1 = / V1 2 - (LA RA V2 LL)/3 = V2 - (LA RA V3 LL)/3 = V3 - (LA RA V4 LL)/3 = V4 - (LA RA V5 LL)/3 = V5 - (LA RA V6 LL)/3 = V6 - (LA RA LL)/3 = Analog KEY = Computation Digital Computation

LL) avf / = 2LL (RA LA) V1 = / V1 2 - (LA RA V2 LL)/3 = V2 - (LA RA V3 LL)/3 = V3 - (LA RA V4 LL)/3 = V4

60 60 12 Lead Respiration, 9 Electrode RLD, 10-Channel Digital Computation Lead Configurations RESPIRATION Wilson = LEAD (RALALL)/3 I = - RA LEAD II = LL - RA LEAD III = LL - LA avr = RA (LA LL) avl / = 2LA (RA LL) avf / = 2LL (RA LA) V1 = / V1 2 - (LA RA V2 LL)/3 = V2 - (LA RA V3 LL)/3 = V3 - (LA RA V4 LL)/3 = V4 - (LA RA V5 LL)/3 = V5 - (LA RA V6 LL)/3 = V6 - (LA RA LL)/3 = Analog KEY = Computation Digital Computation

61 Bio-potential signals Types of bio-potential signals & Common measurements Electro-Cardiogram analog signal chain ECG Lead Derivation Typical ECG System Block Diagram Input Filtering and Defibrillation Protection The INA front end Right Leg Drive (RLD) Amplifier Selection and Design The ECG Shield Drive Lead Off Detection PACE Detection Gain, Resolution and Filtering ADS129x Introduction, Features, and Advantages Lowest power LMP9050x introduction Questions

62 ECG Applications Various types of ECGs ECG Stationary Portable Fetal ECG Patient Monitoring Stress test Holter Monitor Sport Watches Implantable Monitoring

CMRR allow systems to exceed system noise performance of 15 μvpp for diagnostic ECG and 30 μvpp for patient monitors, while consuming under 1mW.

63 LMP90507 Portable ECG Front-End Features Fully integrated Low power ECG Solution Low Power Consumption 300uW/Ch Low Noise 3.5uVrms Analog/Digital Simultaneous Pace signals Hardware AC/DC Lead of Detection Comprehensive error monitoring via alarm pin 5x5mm LLP 95% less PCB over discrete solution Benefits Low noise and High CMRR allow systems to exceed system noise performance of 15 μvpp for diagnostic ECG and 30 μvpp for patient monitors, while consuming under 1mW. Continuous hardware fault detection reduces load on micro-controllers and simplifies software development Synchronization function allows higher lead solutions while using modular implementations Applications VDD VSS Lead off detect LOD_EN Batt. Mon Test Ref CVREF REF LDO VDDDIG RSTB POR XTAL2 XTAL1 VDDIO OSC CLK Low Power Portable ECG & Patient Monitors Wireless ECG, Patient monitoring modules Portable and battery operated ECG Holter Monitors Patches IN1 IN2 IN3 IN4 IN5 IN6 WCT EMI filter EMI filter EMI filter EMI filter EMI filter EMI filter WILSON_CN PACE2WCT WILSON_EN Flexible Routing switch CMDET_EN - CH3-ECG CH3-Pace REF for CM & RLD DRDYB SDO SDI SCLK CSB ALARMB CMOUT RLDINV RLDIN CH1 INA - CH2 INA - CH3 INA - CH4 INA - CH1-ECG Σ Digital Modulator Filter CH1-Pace CH2-ECG Σ Digital Modulator Filter CH2-Pace DIGITAL CONTROL AND POWER MANAGEMENT Wilson ref. CM Detect RLDOUT RLDREF SYNCB SYNCBOUTB SELRLD Σ Digital Modulator Filter CH4- Analog Pace RLD Amp. PACE2 RLDIN EMI filter EMI filter

Thank You! And special thanks to Nichole Oljaca Contact Information: Eric.Li@ti.

64 Thank You! And special thanks to Nichole Oljaca Contact Information: (Sales of TI Shenzhen) (Field Application Engineer) (Business development Manager) Texas Instruments

References 1. JG Webster, Design of Pulse Oximeters, Medical Science Series, Taylor and Francis group, 1997. 2. Beraducci, Mark and Soundarapandian, Karthik.

65 References 1. JG Webster, Design of Pulse Oximeters, Medical Science Series, Taylor and Francis group, Beraducci, Mark and Soundarapandian, Karthik. Sbaa160, Application Report: Analog Front End Design of ECG Systems Using Delta-Sigma ADCs. March Brown, John and Joseph Carr. Introduction to Biomedical Equipment Technology. Prentice Hall Inc. New Jersey. 1981, Fraden, Jacob. Handbook of Modern Sensors Physics, Designs, and Applications. Advanced Monitors Corporation. San Diego Graeme, Toby, Huelsman. Operational Amplifiers Design and Applications. McGraw- Hill Publishing Company. New York Gray, Paul R. and Meyer, Robert G. Analysis and Design of Analog Integrated Circuits. John Wiley & Sons. New York. 1977

Analog Fundamentals of the ECG Signal Chain

Analog Fundamentals of the ECG Signal Chain Prepared by Matthew Hann, Texas Instruments Precision Analog Applications Manager Presented by Jose Duenas, Precision Analog Product Marketing Engineer 1 Objectives