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Improved Howland Current Pump Stability

Improved Howland Current Pump Stability. Tim Green Senior Analog Applications Engineers Precision Analog Linear Applications July 19, 2013. Improved Howland Current Pump IL Accuracy Circuit. RT allows for trim to optimum Z OUT and improved DC Accuracy. Ideal Op Amp.

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Improved Howland Current Pump Stability

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  1. Improved Howland Current Pump Stability Tim Green Senior Analog Applications Engineers Precision Analog Linear Applications July 19, 2013

  2. Improved Howland Current PumpIL Accuracy Circuit RT allows for trim to optimum ZOUT and improved DC Accuracy Ideal Op Amp

  3. Improved Howland Current PumpV-I DC Accuracy Calculations 1% Resistors (w/RT=0) could yield only 9% Accuracy at T=25°C Still useful for V-I control in Motors/Valves  V-Torque Control Outer position feedback adjusts V for final position

  4. Improved Howland Current PumpSimplified Equation

  5. Improved Howland AC Analysis RI RF Op Amp sees differential [(-IN) – (+IN)] feedback b=b- -b+ (Must be positive number else oscillation!)

  6. Improved Howland AC Analysis - +

  7. Improved Howland 1/b Plot - Full Load

  8. Improved Howland 1/b CalculationNo Load & Full Load Change in RO from No Load to Full Load has no significant impact on the 1/b Plot

  9. Improved Howland Tina Transient Analysis Circuit RI RF

  10. Improved Howland Tina Transient Analysis Results

  11. Improved HowlandModified 1/b for Stability

  12. Improved Howland AC AnalysisFinal Design for Stability RI RF

  13. Improved Howland AC Analysis1/b - Final Design for Stability fcl

  14. Improved Howland AC AnalysisLoop Gain - Final Design for Stability fcl

  15. Improved Howland AC Transfer AnalysisIL/VIN - Final Design for Stability RI RF

  16. Improved Howland AC Transfer AnalysisIL/VIN - Final Design for Stability

  17. Improved Howland Transient AnalysisIL/VIN - Final Design for Stability RI RF

  18. Improved Howland Transient AnalysisIL/VIN - Final Design for Stability

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