The World Leader in High Performance Signal Processing Solutions

Medical ApplicationsElectrocardiogram (ECG)

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Glossary of Terms AED Automated External Defibrillator – Auto diagnosis with

voice directed treatment. EKG/ECG ElectroCardioGram – skin surface, heart

monitor Holter Monitor Portable device for continuously monitoring

the electrical activity of the heart for at least 24 hours. Can be external or implantable.

Defibrillation Delivering a therapeutic dose of electrical energy to the heart.

T-wave alterans A change in the shape of the heartbeat signal on an every other beat basis that is not apparent to the naked eye.

Right Leg Drive An operational amplifier deriving common mode voltage is used to invert the common-mode signal and drive it back

into the patient through the right leg. RFI Radio Frequency Interference ESD Electro Static Discharge

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ECG Markets ECG

Professional Healthcare Consumer

Diagnostic

Above Diagnostic

AED

Defibrillators

Commercial Fitness Equipment

Home Products

line battery line battery

Holter Monitor

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ECG Waveform (Filtered)

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ECG – Waveform Characteristics

ECG Signals have two components: ECG Waveform

0.05 Hz to 150 Hz bandwidth per Medical StandardsAverage R Wave Amplitude is 1.8mVSome waveforms can be as big as 10 mV p-p.T wave Alterans are only a few microvolts in amplitude

Pacing ArtifactMedical Standards require 2mV and 200µs detectionAverage pulse is 1 mV and 500µs but can be much smaller

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ECG – Patient Skin Surface Characteristics

Skin ImpedanceStandards require of common mode rejection at 51K ohms skin to

electrode impedance at 10HzGood Silver-Silver Chloride electrodes yield about 10 K ohm

electrode to skin impedanceStainless Steel electrodes can yield skin impedances of several

meg-ohmsDefibrillation Voltage

5000 volts, 360 JoulesDC Voltage

Medical Standards require being capable of acquiring ECG with 300 mV of DC. Mostly due to half cell potential of electrodes, stainless steel can yield 500 mV of DC

60 Hz NoiseAverage is several mV

The World Leader in High Performance Signal Processing Solutions

Signal Chains

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Diagnostic ECG (Clinical Use)

AD8220

InstrumentationAmplifier

+5V

-5V

A B

C

24.9kΩ24.9kΩ

AD7980

ADum240X

BlackFin

ADC

DSP

iCoupler

REF 22μF

ReferenceADR435

4.12kΩ

Additional Channels

Additional Channels

AD8618

+5V

4.7μF

14kΩ

+5V

+5V

-5V +5V

-5V

REF/2

REF/2

1MΩ

47nF

10kΩ

10kΩ

2.2pF

2.2pF

10pF

G=14

12.7kΩ 12.7kΩ

866kΩ

68pF

499kΩ

OP2177

+5V

OP2177+5V

op amps-5V

-5V

AD8618

+5V

14.5kΩ

14.5kΩ

68nF

22nF

REF/2

LowPass 5th OrderFilterat 157Hz

switchADG601

FromLead I

FromLead IIFromLead III

ADum240X

AD8618

+5V

19.3kΩ

19.3kΩ

33nF

33nF

220pF

REF/2Pacing Artifact

Detection Circuitry

15kΩ

LeadDetection

50kHz

866kΩ

ADG620

REF/2

AD8618

+5V

57.6kΩ1.18kΩ 14kΩ

HighPassFilter 0.033Hz G=50

1.15kΩ

4.99kΩ

33Ω

10nF

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Diagnostic ECG In-amp + Right Leg Drive

AD8220

InstrumentationAmplifier

+5V

-5V

A B

C

24.9kΩ24.9kΩ

4.12kΩ

4.7μF

+5V

-5V +5V

-5V

REF/2

10kΩ

10kΩ

2.2pF

2.2pF

10pF

G=14

12.7kΩ 12.7kΩ

866kΩ

68pF

499kΩ

OP2177

+5V

OP2177+5V

op amps-5V

-5V

switchADG601

FromLead I

FromLead IIFromLead III

220pF

15kΩ

866kΩ

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Diagnostic ECG Filters + Pace Detection

AD8618

+5V

4.7μF

14kΩ

REF/2

REF/2

1MΩ

47nF

12.7kΩ

AD8618

+5V

14.5kΩ

14.5kΩ

68nF

22nF

REF/2

LowPass 5th OrderFilterat 157Hz

switchADG601

FromLead IIFromLead III

AD8618

+5V

19.3kΩ

19.3kΩ

33nF

33nF

220pF

REF/2Pacing Artifact

Detection Circuitry

LeadDetection

50kHz

866kΩ

ADG620

REF/2

AD8618

+5V

57.6kΩ1.18kΩ 14kΩ

HighPassFilter 0.033Hz G=50

1.15kΩ

4.99kΩ

33Ω

10nF

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Diagnostic ECG ADC + Isolation + Processing

AD7980

ADum240X

BlackFin

ADC

DSP

iCoupler

REF 22μF

ReferenceADR435

Additional Channels

Additional Channels

+5V

ADum240X

33Ω

10nF

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Low Power, Low Cost, Wireless ECG (Holter Monitor)

ESDDefibrillationProtection

ADuC7022

ADF702x*

ESDDefib

Protect

RLElectrode

RAElectrode

RLElectrode

AD623G=10.6

High-PassPole0.5Hz

0.47μF

5pF

681kΩ

499kΩ

5.23kΩ 5.23kΩ

475Ω 10kΩ

108pF

Anti-aliasFilter-3dB, 1592Hz

AdditionalDigitalFilter

Level ShiftAnti-Alias

TotalGain ~ 220

G = 22.05

AD8641

AD8603

Dependent onFrequency BandUsed(WMTS or ISM)

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Low Cost, Low Power AED

Filterand

ProtectionNetwork

ADR365

AD7685

HighVoltage

Discharge

PowerControl

ADP1712

AD8220/4AD8606

AD8605

PatientPads

Li IonBattery

ADuC70xxor

Blackfin®

LCD Display

Single poleanti-alias

filter

Digital Filtering

Blanking

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Exercise Heart Rate Monitor (Example: treadmill with heart rate monitor)

AD8692AD8692

REF

REF REF

AD8553

AD8691

HighPassFilter

ADuC70xxREF

InputProtection

+5V

40HzLowPassFilter