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Analog Electronics Class 4 CMRR, PSRR, Vcm Range, Output Swing

Analog Electronics Class 4 CMRR, PSRR, Vcm Range, Output Swing. Oct 10, 2011. Common Mode Voltage Range. Common Mode Voltage Def:. REAL WORLD Inputs. Typical Bipolar or JFET Input (not rail-to-rail). Simplified schematic of OPA827 input stage. Simulate Vcm Range. Simulate Vcm Range.

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Analog Electronics Class 4 CMRR, PSRR, Vcm Range, Output Swing

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  1. Analog Electronics Class 4CMRR, PSRR, Vcm Range, Output Swing Oct 10, 2011

  2. Common Mode Voltage Range

  3. Common Mode Voltage Def:

  4. REAL WORLD Inputs

  5. Typical Bipolar or JFET Input(not rail-to-rail)

  6. Simplified schematic of OPA827 input stage

  7. Simulate Vcm Range

  8. Simulate Vcm Range

  9. Simulate Vcm Range Simulated and data sheet don’t always match

  10. MOSFET Simple Input(not rail to rail)

  11. Simplified schematic of OPA336 input stage

  12. MOSFET Complementary N-P-FET (rail-to-rail)

  13. Simplified schematic of OPA703 input stage

  14. MOSFET Complementary N-P-FET (rail-to-rail)

  15. MOSFET Charge Pump (rail-to-rail)

  16. MOSFET Charge Pump (rail-to-rail) • Supplies a small current to input • GBW = 50MHz, Charge Pump Freq=10MHz

  17. MOSFET Zero Drift (rail-to-rail)

  18. MOSFET Zero Drift (rail-to-rail) With Offset Correction No Offset Correction

  19. Common Mode Rejection Ratio

  20. CMRR Specification CMRR(dB) = 20 Log (ΔVosi / Δ Vcm) (data sheet) CMRR(Linear-Gain) = 10(CMRR(dB)/20) (solve for linear gain) CMRR(Linear-Gain) = ΔVosi / Δ Vcm

  21. Note: Vos is defined for this condition. Vcm = Vs/2 Vs/2 = GND in this case Note: Vos is affected by Vcm. Vcm = Vs/2 + 12V

  22. AC CMRR Example OPA170 Vcm = Vin Vcm = 0V Vcm = Vsupply / 2

  23. AC CMRR Example OPA170

  24. AC CMRR Example OPA170

  25. AC CMRR – Run Transient

  26. AC CMRR – Transient Results

  27. AC CMRR – Simulated vs. Calculated

  28. Power Supply Rejection Ratio

  29. AC PSRR Simulation ExampleOPA170 Set up the AC source. 1V @ 1kHz in this case.

  30. Output Stage Considerations

  31. REAL WORLD Outputs

  32. Typical Rail-to-Rail Input/Output Topology

  33. Op Amp Output Range Consideration

  34. Achieving Output Swing tothe Op Amp Negative Rail

  35. Classic Output Stage • Common-emitter output • Current source driver • Headroom set by VBE+VCESAT • Unity Gain

  36. OPA827 OPA827 OPA827 – Classic Output

  37. R-to-R Output Stage • Common Collector or Common Drain • Headroom set by VCESAT

  38. R-to-R Output Stage • Common Collector or Common Drain • Headroom set by VCESAT • Value of RLOAD affects AOL

  39. OPA211 – rail-to-rail Out

  40. OPA209 Output Swing Range

  41. OPA209 Output Swing Range

  42. Homework

  43. 1. Calculate and simulate the output offset for the following circuits.

  44. 2. Calculate and simulate the swing to the rail limit for the following circuits.

  45. 3. Calculate and simulate the effect of the ac source on the power supply .

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