a bad tape-out experience about a bandgap voltage reference

[liuyonggen_1]

could someone help me?
tha attachment is the structure of bandgap voltage reference. the simulation result showed that the output is about 1.12v with 10ppm.


but when I measured it after taped out, the output voltage is about 0.7v.

the following will show you the performance of the elements.
the threshold voltage of the BJT is about 0.8v. its current gain is about 10 (very small). maybe, the matching between the resistance is bad.

could you explain it for me ? thanks a lot!

 

[MikeR]

What is Vdd and R1/R2/R3 ratio ?

 

[horzonbluz]

Re: a bad tape-out experience about a bandgap voltage refere

The structure of your bangap is wrong.
I don't think it can afford a 1.2V output voltage.

 

[aryajur]

Re: a bad tape-out experience about a bandgap voltage refere

Did you try sweeping the Vdd to higher voltage?

 

[liuyonggen_1]

Re: a bad tape-out experience about a bandgap voltage refere

the vdd is about 5.8v
yes ,i sweep the vdd to about 10volts, the output voltage is about 1.2v. but when continue to increase the vdd, the output voltage will also increase.

Added after 2 minutes:

The structure of your bangap is wrong.
I don't think it can afford a 1.2V output voltage.

could you explain it in detail? thanks a lot!

 

[gdhp]

i think you can explain your structure first.

 

[liuyonggen_1]

Re: a bad tape-out experience about a bandgap voltage refere

i think it's a basic voltage reference structure.

 

[xiaoben]

Re: a bad tape-out experience about a bandgap voltage refere

first you will check you circuit ,then you must simulate the circuit and check the DC operation point,at last .at last to solve the problems.

 

[liuyonggen_1]

Re: a bad tape-out experience about a bandgap voltage refere

the simulation results shows that the circuit work normally. but the measure result shows as the above said.