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Bandgap Startup Circuit

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44 Threads found on Bandgap Startup Circuit
Hi Guys, I have a concern on the bandgap start up circuit design. I understand the need of a start up circuit in the bandgap design. But I'm not very sure, or need your feedback on the simulation outcome that Im observing. With the startup circuit added, the bandgap core (...)
I would suspect that the Schmitt threshold is too close, but on the wrong side of, the bandgap output voltage and yet the startup circuit cannot be removed without the bandgap core collapsing. The startup looks too simple to me. Start with breaking that feedback loop and see where the (...)
You could start with just what "didn't work" means. A result you didn't like, or failure to produce a result at all? bandgap / PTAT loops without explicit startup mechanisms, can easily converge in one testbench and fail in another, because when they start up they're doing so on "numerical noise" which depends on the circuit matrix and (...)
Hi all, I am designing a bandgap reference circuit, which i have tested using Cadence Spectre. The circuit works well and converges to the designed operating point without a startup circuit, which wont be the case, when fabricated. The problem now is, if i design a startup (...)
The problem with all capacitive-based startup circuits is that it's not robust. You may have to simulate not only slow startups, but also brownout conditions. It may give a lot of headache if you have very strict criteria on your bandgap startup.
Hi Guys: I am working on a bandgap circuit for a internal regulator in a DC-DC converter. The core circuit is a simple BROKAW bandgap circuit and i need a startup circuit for it.The problem is the input voltage is from 5~23 and the high voltage MOSFET my process provide (...)
Hi Friends I am designing a bandgap reference circuit in .18um process shown in figgure. my objective is to get a stable output voltage with least temco as possible when i simulated my bandgap i got 1.125v as the voltage which has least temp co but usually 1.25v is the desired bandgap voltage if i set my output voltage to (...)
Some bandgap structure will have three operating points.
Will the bandgap ref work well if I add 2 cap and 2 res in the circuit? startup without any problem? stability for work?
Hi all, Could someone help me with the startup problem in my bandgap circuit? I have startup problem for lower temperatures .i.e if i simulate ckt for weak -40. I get output waveform as attached .. Thanks in advance rampat
You are asking far too general a question. You really need to read some books on bandgap design. Bumping the same question won't get an answer. Keith.
Hi All, I have a bandgap reference circuit, which works fine in simulation. (Both DC temperature sweep and transient sweep give satisfactory results.) As this is my first fabrication, I am a bit concerned about the start-up and also the stability of the circuits. startup the startup (...)
Hi this bandgap the startup circuit works fine untill I apply an offset (vos) to the opamp. With a positive offset, all it's ok but witha negative one the loop becomes open! Why does it happen? Any suggestion to avoid this bad behavior, please? TIA, CBs
hi, would you pls suggest a startup circuit for Conventional BGR,which consumes less current(in nA) and improves the response of the bandgap? Thanks
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 ch
1.what is your initial seting for your circuit or why you do that? Becuase you have an inable pin? 2. The mean state is a stable state and in this state the VBGR will not start ever without start-up circuit. I designed bandgap voltage reference and startup circuit for it. I have read topics about BGVR (...)
A simple test, simple to automate, is that your circuit should be enter the normal mode from any node voltage combinations. If you have 9 nodes you have possible 512 states where either VDD or 0 is used as initial state. Some of the state lead to high currents or some very short time responses. But there are possible states where is takes very l
hi i attch the bandgap circuit. Do we need start up circuit for this bandgap and why? thanks
you can search and get many resources about bandgap references here.
Hi all I've a question about bandgap reference circuit. In attached figure, left side is bandgap core & right side circuit is my question.... I heard that right side circuit prevent saturation when start-up. But I don't know further. Anyone can help me?
is there any way that i can check functionality of my bandgap circuit in SPICE simulation without using start up ckt. And is start up ckt always required for bandgap functioning???? also suggest some good start up circuits fro bandgap references????
Thanks all the friends to reply to my question. The problem i stated above have been resolved.I added a capcitor between power supply line and the output of opamp, in this way, the voltage at two pmos transistor's gate will not be so sharp, additionally, i reduced the total capacitance at the opamp's output node to alleviate it's bu
I found the start up circuit for a bandgap is difficult to work well at different Vcc supply. For example, 2.7v and 3.6V. When the Vcc is high, the start up circuit can not shut up completely and when the Vcc is low, the startup circuit can not bias the bandgap core (...)
Transient analysis is enough to simulate a bandgap circuit.
Have you built a start up circuit in your bandgap circuits?
Do you know any book or ref to design the startup circuit for bandgap both in cmos and bicmos process. Please advise. thanks
hi, i'm design a bandgap voltage and simulate it with hspice. how can i simulate and validate my bandgap design correct or not without using startup circuit? is it using .tran xx xx uis and .ic v(x)=xx to initialize some node to the specific voltage? thanks.
Try this link: and goto Start-up circuitry section .. Regards, IanP
I need startup circuit for bangap voltage reference and value for R1 and R2. VDDA=5V
There are few such materials about startup circuits for bandgap in IEEE. Where can I find relative materials? Thank you there is one start up circuit in the chaper of bandgap in Razavi's book
To sunking, It is for bipolar version bandgap. Is there any similiar circuits for CMOS bandgap ?
if the circuit is self-biased it contains a zero solution. let's say your circuit uses an amplifier or level shift stage. if this current is set by the bandgap then the bandgap has to be running for that current to exist. also, that current must exist to allow the bandgap to run. this would be one (...)
in my opinion, it can not filter the high frequency noise from the power supply, and it can delay the outputs ,but do the outputs really need the delay? or there are some other functions this capacitor can perform? thank you very much:)
Every POR should using RC charge up mechanism. I think you may make mistake between por and startup circuit. startup circuit usually is used together with bandgap to make bandgap circuit enter normal working state.
Where you add the cap? If you add a cap C shunted to the R, the C and CgsMS would form a capacitive divider, this turn on the MS and make the bandgap start faster then charge MS through R.
You should design the power-down and start-up circuit for the bandgap voltage reference at the same time. Several types of Start-up circuits for CMOS BGR are for your choice. 1. Cap. based Start-up Tha capacitor is initially zero which leads to the current generation in BGR loop and consequently, current mirror starts to charge the (...)
For a bandgap, i have simulated some parameters, such as: 1. the PSRR; 2. the output impedance; 3. the input referred noise; 4. the temperature coeffient; But the three sides : startup circuit, frequency and stability . i do not know how to simulate them. for startup circuit: I done: 1) the dc (...)
I consider what you think is right. Without the startup circuit the bandgap reference circuit has two stable state, so you must use .ic command to set the circuit to another stable state. So with or without the startup circuit you can see the difference.
I have a bandgap with 2 startup circuits. When I run a transient analysis it takes very long to simulate. This has to do with the output waveform shown below. Is the circuit unstable? Or does it has to do with the 2 startup circuits? By the way I am ramping the Vdd signal and (...)
how to design low current bandgap ?? Vcc=3.3v target is bandgap block =1ua vbg= 1.25v .. if use low current design use "CMOS circuit design layout & sim " CMOS cascode bandgap architecture
I have a problem . I have to simulate operational ampliofier of one bandgap, but to include capacitances of all transistors connected to the output of the operational amplifier, I started to simultate the amplifier as a part of the bandgap. But there is a problem the output of the amplifier sets to 0V, The output to of the bandgap goes to (...)
Is it possible to have the wideswing current mirror for bandgap circuit. Does this work properly in silicon. Where do I need to have the start ups. (please see the attachment for circuit) thanks in advance.
I am attaching two bandgap schematic here. The schematic in fig(1) is not working fine. but fig(2) works. Whats the reason behind this. what exactly the difference between these two schematics. thanks in advance.
The main circuit is the PTAT core. It is enclosed into a regulation loop which try to equalize the currents I1 and I2. The resulting current IPTAT=I1=I2 is the PTAT current. The equations for the PTAT circuit is I1*R+VT*ln(I1/(a*IS))=VT*ln(I2/IS), "a" emitter area ratio the solution for I1=I2 is IPTAT=I1=I2=VT*ln(a)/R Issue1: I