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ECG n

The INA Front End Determining MAX Gain for the RLD Amplifier. V ECGp + V ep + V CM. ECG p. V ep. R A. R G /2. R G /2. R A. More Gain = Better CMRR Gain Limited By Electrode Offset (MAX = ±300mV), VOS A1 , and VOS RLD. R F. V en. ECG n. V REF. R I. V ECGn + V en + V CM.

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ECG n

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  1. The INA Front EndDetermining MAX Gain for the RLD Amplifier VECGp + Vep + VCM ECGp Vep RA RG/2 RG/2 RA More Gain = Better CMRR Gain Limited By Electrode Offset (MAX = ±300mV), VOSA1, and VOSRLD RF Ven ECGn VREF RI VECGn + Ven + VCM

  2. The INA Front EndRL Drive Stability Simulation Circuit Electrode Resistance Varies With Contact and Moisture, Presents Problems for RLD Stability Local RLD Loop is Broken to Ensure Proper Phase Margin Over Range of Electrode Resistance

  3. The INA Front EndRL Drive Simulation Showing 1/Beta Variation With Electrode Resistance > 20dB/dec ROC (Rate of Closure) = INSTABILITY AOL Relectrode = 100kΩ Relectrode = 1kΩ

  4. The INA Front EndUsing RLD Simulation to Compensate for 1/Beta Variation With Electrode Resistance Variation in AOL vs. Process Intersection of 1/ß and AOL curve > -40dB/dec Feedback Comp Placed vs. Worst Case Electrode Resistance and RLD AOL

  5. The INA Front EndRL Drive Stability Simulation Circuit of Feedback #1

  6. The INA Front EndRL Drive Stability Simulation Circuit of Feedback #2

  7. The INA Front EndRL Drive Stability Simulation of Separate Feedback Paths AOL Feedback #1 Feedback #2 Composite 1/ß

  8. The INA Front EndRLD Stability Circuit with Compensated Amplifier

  9. The INA Front EndCompensated RLD Circuit Simulation of 1/Beta and AOL Intersection Intersection of 1/Beta and AOL curve is 20dB/dec = STABLE

  10. The INA Front EndGain and Phase Margin Plots of Compensated RLD Amplifier Loop Gain Phase Margin @ 0dB = 70 degrees

  11. The INA Front EndStep Response of RLD Amplifier and ECG Output

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