Search Engine www.edaboard.com

Startup Circuit Bandgap

Add Question

44 Threads found on edaboard.com: Startup Circuit Bandgap
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 (...)
Add some deliberate leakage (a very low current source or large resistor) to prevent it starting. Then add the startup circuit and check it does start. You may be able to do it with "initial conditions" although I usually add deliberate leakage. Keith
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 (...)
this architecture is bad for low voltages. I like it since it is reliable. In your case you probably will have a bit high current through startup circuit - but you can fix it. Temeperature coefficiant - you can try to play with 1:n ratio. I noticed in my case that if I use usual 1:8 or 16, it does not work well so I went to 132 and made my own bipo
a) startup during transient sims b) set transient to conservative
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
hi all, i wanna do some research about the startup circuit of bandgap, please help me 1:how to analysis the numbers of the stable operating points of the circuit. as far as i know, some bandgap circuits have 2 stable operating points, some circuits have 3 stable (...)
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
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
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 Surianova, Yes in this circuit u very much need the startup circuit... This circuit has two stable states one with zero current and other one with defined branch currents... and the second state is desired. So to pull it away from first state and pushe it into second one we need to inject some current into its branches
Try using a schimitt trigger to genarate a pulse use that pulase to urn on the mos connected to which ever node u want to inject current into... You can modify the "on" time of pulse according to ur worst case ... Once the pulse goes off startup mos is off. This the basic idea... Ihave implemented in my bgr .... It works fine!
So it has only startup function? Are there any other function???
If you are doing a transient run then startup is required.If you do OP simulation then startup may not be required for the simulation. Jitendra Dhasmana.
I think your startup circuit gives additional current during 1V step and as a result you get overshoot.
go for the bekar book for startup circuit
Transient analysis is enough to simulate a bandgap circuit. but simulation startup must do rampup you can tyr it
bandgap reference voltage is ossilating before it reachs to ref level during startup. Help me to solve this problem.
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.
hi can anyone of u suggest me a good paper or a link to design the startup circuit for the bandgap reference. If u have the circuit then can u pls upload it. thanx in advance
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
Does the brokaw-cell bandgap reference need the startup circuit?? Thanks
If a current reference circuit doesn't exit zero solution, does it need a startup circuit or not?
1. startup cap. 2. it must be compensation cap of the feedback loop.
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.
For the startup circuit below used for bandgap I have found that for a fast ramping of supply voltage (10us) it takes a while for the bandgap voltage to reach steady state >10us, under different corners. However if you put a MOS cap at the current mirror this issue is solved. Can anyone explain why is this so? For slow (...)
Is that possible to design the power-down and start-up circuit for the bandgap voltage reference at the same time? When I add the startup circuit for my bandgap, then the power-down isn't work anymore. Anyone can recommend the paper or examples about badgap with both of power-down and (...)
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.
The possible oscillation is not in the basic PTAT loop but in the take over circuit for the initial startup. Isolate the startup by using an constant current source as startup instead.
If the A or B is used as bias for gate of PTAT current, i think the circuit will not work. Generally , the statup circuit generates the current for core circuit, once the core circuit work normally , the startup circuit is isolated from the core circuit. AS you draw , (...)
Usually bandgap circuit need a startup circuit to bring it out of initial condition, i.e., 0v or Vdd. So, I guess you can either include the startup circuit or set correct .ic when simulating.
it can work. it design for a low supply voltage. you should add a startup circuit at the gate of Q12&Q6 or Q16&Q3
The circuits look equivalent to me. I think that the negative feedback action described by hylas also happens in the other circuit. However both these circuits NEED a startup circuit. If you don't have a startup circuit it may happen that your simulation indicates that one (...)
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