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Ballpark Numbers
There are a lot of process numbers which are quite common across processes and good to have handy to know what can be achieved in a design.

  • The variation of an untrimmed bandgap made using Vbe and resistors is usually +/-3% and we add a trim range of +/- 4.5 to 5%
  • For an untrimmed bandgap the temperature variation of the voltage at extreme corners may be like +/- 0.5% (~6mV) or +/-1% (12mV if taken to 150C) from the room voltage, while that of a trimmed bandgap may be <+/-0.2% (2mV).
  • Capacitances vary about +/- 16%
  • MOS gate cpacitance is more tightly controlled and is about +/-10%
  • Resistor variation depends on the width of the resistor and polycrystalline resistors can vary anywhere from +/- 50% to +/-10% (PI)
  • Bipolar Vbe varies about +/- 2.5% over process corners (room temperature)


  • For small power supply adapters the transformers made to switch at 100KHz and close frequencies usually have capacitance like in the 10s of pico farads so have parasitic loading of 100pF on the switching transistor can be reasonable.

Copyright 2018 Milind Gupta