General Questions about Bandgap Reference

Discussion in 'General Electronics Chat' started by aredhel_vlsi, Nov 4, 2009.

  1. aredhel_vlsi

    Thread Starter New Member

    Aug 22, 2009
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    Hello everybody, could I have some general info about the design of Bandgap Reference Voltage?

    1) What kind of effects can somebody meet at a bandgap reference?

    The offset at the input of the opamp, is one, as far as I know. Also there are the second order effects, which are met in mos transistors, such as channel length modulation (is that the same with Early Voltage effect?),Body effect, subthreshold region, mobility variation, impact ionization. anything more specific?

    2)a)what kind of temperature analysis error about the temp coefficient can sombody meet? 0.3 % relative variation is good enough?

    2)b)temperature analysis is a systematic error? so that meas it is because designer's mistakes?
    3)what other software tools can be used except cadence? I've heard something about magic. which is better for layout and simulations?

    4)what kind of a noise margin do typical bandgaps have got? I mean, how much?

    5)what is the upper limit about consumption in Amperes? 0.5 mA is considered to be very high about 1.8 V supply voltage? do I have to check the whole consumption of the circuit, or should I check the nets separately, and ignore the startup consumption (which will turn off later)?

    6) what kind of gain have got opamps in a bandgap?

    7)Is it better to use diodes or BJTs at the bandgap core?

    8)what is the lowest in um design that has been published until now?

    Too many questions? I think I know some answers merely, but I want to have a general idea, especially in numbers. ie, 30dB gain, 1mA consumption etc.
    Any ideas welcomed!
     
  2. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    If only Bob Pease was here.....;)
     
  3. bertus

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  4. t_n_k

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