Circuit Characteristic of Bandgap reference

Hi there,

I am a analog behavioral modeling engineer. I am developing analog power supply behavioral model now. I will develope "bandgap reference model" by using AMS language. During the development i wish to verify the following charasteristic:

1. start-up characteristic: Vout vs Vin
2. load characteristic: Vout vs Iload
3.temperature characteristic: Vout vs Temp
4.Supply voltage charateristic(I am not very sure about how it should look like)

Can anyone please kindly suggest me how to verify the above mentioned characteristic and please kindly attach any avaible waveform of how it should be looked like.

p/s: actually i am developing charge pump, 5v regulator and a driver circuit AMS model for power supply as well.

Thank you ver much.

Interessting problem...

I know how to figure the waves and could also point into the circuit reason but thinking of the right differential equation giving the same response is tricky!

The best start would be the loop gain equation of the kT-generator and using a first order integration. That should show the slow intial startup. The next point is that the loop gain is affected by the supply voltage, e.g. the output follows first the supply then set to his own point.

Do you know how the kT-generator works?

Can you explain how the KT-generator works?

By the way, do you how to verify load characteristic ?

I assume that you know the circuit but want to know the expression behind the loop gain.

Take a minute ... I will try to do it here on the keyboard


Want to define the current loop gain where the two bipolars share a common emitter with one having a resistor in series with his emitter.

Gain(I)=exp(log(a)-I*R/Vt)=a*exp(-I*R/Vt)

ok I think that is the expression

The factor "a" define the emitter area ratio of the two emitters. I*R/Vt is the relative voltage drop across the resistor. The stable operating point is where Gain(I)=1. That is if the mirror ratio is 1. You can describe the loop current as state variable. A first order for the mirror but with pole frequency dependend on current level. The same for bipolar pair. Both components connected in a loop. That is about the beginning of the model.

The output load could be verified by load current versus output voltage. Typical linear up to a knee current then drops.