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Page 1: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Voltage  reference  and  bandgap  circuits  

Page 2: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Basic  blocks  for  voltage  reference  circuits  

Page 3: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Characteris8cs  of  bipolar  transistors  

Page 4: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Temperature  dependence  of  BJT  characteris8cs  

Page 5: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Temperature  dependence  of  ΔVBE  

Page 6: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Temperature-­‐compensa8on  of  VBE  voltage  

Page 7: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Temperature-­‐constant  Reference  Voltage:  “Bandgap-­‐Reference”  

Page 8: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Opera8on  of  Bandgap-­‐Reference  Circuit  

Page 9: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Bandgap-­‐Reference  Circuit  

Page 10: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Gummel  plot  of  BJT  

Page 11: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Startup-­‐Problem  of  Bandgap-­‐Reference  Circuit  

Page 12: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Adjustment  of  bandgap  reference  voltage  

Page 13: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Undervoltage  detec8on  circuit  based  on  the  bandgap  reference  principle  

Page 14: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Undervoltage  detec8on  circuit  

Page 15: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

CMOS  Compa8ble  Bandgap  Reference  

Page 16: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Bandgap  reference  with  all  npn-­‐collectors  connected  to  VDD  

Page 17: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Bandgap  reference  in  a  n-­‐well  CMOS  technology  

Page 18: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

„Widlar“  Bandgap  –  Reference  

Page 19: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Current  -­‐  Reference  based  on  ΔVBE  

Page 20: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Cross-­‐coupled  current  source  based  on  ΔVBE  

Page 21: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Adjustable  Z-­‐diode  

Page 22: Voltage(reference(and(bandgap(circuits( - MiXeDsIgNaL · „Widlar“ Bandgap(–(Reference (Current(=(Reference(basedon ΔV BE. Crosscoupled (currentsource( basedon ΔV BE. Adjustable(Zdiode

Z-­‐diode  voltage  mul8plier