Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Absolute value accuracy of CMOS bandgap

Status
Not open for further replies.
B

BlueSkyPrairie

Newbie level 4
Joined
Apr 10, 2009
Messages
5
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,351
From what I read, the absolute value of a CMOS bandgap using substrate PNP is affected mainly by mismatch in the PNP. op. amp. offsets, current mirror mismatch, resistor mismatch. If the circuit is well designed, large W, long L, wide R, and well layout. What is the absolute variation in the bandgap voltage that can reasonbly be obtained, within 0.5%, 1%, 3%, 5% of the nominal bandgap value ?
 

Bandgap voltage spread depend on resistor spread for the kT-generator and IS spread of the bipolar. Both depend on process control.

Vbdg=b*VT+Vbe=b*VT+VT*ln(VT*ln(a)/(R*IS))

a: emitter area of kT-generator
b: kT-multiplier
R: resistor kT-generator
IS: saturation current

Vbdg=f(R*IS)

So the relative spread is

Vbdg,spread,rel=26e-3*log(1+spread(R*IS))/1.25
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top