Please help me on this reference circuit..

[alicia8283]

hi all,

could anyone please explain to me the operation of the circuit below? i know this is a bandgap but i confuse for the part Q3, R and why there is a cap.

Q1=8Q2



Thanks a lot first.

another question is, what is the difference between model "nanch3" with "nch3" for TSMC .18u process?

 

[alicia8283]

hi, could anyone please help to explain the operation of the circuit? i am much appreciated.. thanks

 

[ljy4468]

What is the purpose of MNN2?
and node dp13 is connected to other nodes?

 

[jianjing526]

Q3 connected as a diode to provide a CTAT voltage. PTAT current flows from R3 to provide a PTAT voltage. Left side circuit including MNN2 seems to be a startup one. caps here is to stabilize the reference voltage!
nanch3 is a n-channel mosfet which acts as a native transistor. No threshold adjustment mask will be added in the fabrication process!

 

[allan_guo]

I think:MNN1&MNN2 must be depletion nmos.MNN1 is used for start up,MNN2 is for reduce system error

 

[alicia8283]

hi guys,

Thanks a lot for your reply.

hi Allan_guo, could you explain further how MNN1 used for startup? and more detail explanation on MNN2 to reduce system error?

Initially i thought MNN2 is as startup circuit for this bandgap.

hi jianjing526,
nanch3 is native transistor and no threshold adjustment mask added, does it means that there is no extra layer needed for this MOS? Am i correct?

Thanks again for your reply.

 

[saro_k_82]

The start-up circuit IMO consists of MNN2, MP13 and MP14. MNN1 must be a depletion mode transistor shielding against early voltage induced errors.