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49 Threads found on edaboard.com: Bandgap Layout
Do the dkit mismatch models work correctly when resistors which should be matched are not in common-centroid layout? For example, a coleague designed a bandgap reference, and its design has three resistors that should be matched, but when he draw the layout, he put the three resistors in thi way. R1 R2 R3 (R1, R2 and R3 are made up of (...)
In band gap circuits, in layout if we have bjt 1:8 or 2:16 ratio the matching is done in such a way by keeping one bjt in centre and the remaining 8 surrounds the centre one(3X3) format.Can any explain the reason behind these matching concept?? thanks in advance
Hi Guys, I have a concern on the bandgap design. I have covered the process/voltage/temperature + montecarlo simulations on both the pre layout and post layout simulations, and the result are in the expected range with typically ~1.2V of the bandgap output voltage. The montecarlo simulations were performed around 1000 (...)
Hai everyone,this is Pallavi.I am going to complete my training in custom layout(industrial oriented) training by this August with the following designs: 1.Standard cells-INV,AND,NAND,NOR,XOR,MUX,OAI,DFF 2.Analog circuits-LevelShifter,Op-amp,bandgap,DAC,PLL can any of you please refer me to have a better careerpath in my life. Hoping you will..
Hi, I am currently debuging the bandgap and LDOs peaking at 3V power supply problem; please refer to the attachment 70540 the norminal VDD is 3.3V, and I look at the schematic, simulation results shows OK, no much variation with power supply change, also the phase margin of LDO is 53 degree, also layout should be ok too
Hi, currently I'm designing a bandgap voltage reference. I need some recommendations on the software(s) that able to draw the schematic and simulate it for the results, at the same draw the layout. I have Mentor Graphics in campus but unfortunately, it's closed on weekend. I have to work from home now. I need a solution (Freeware) ASAP! I have
Hello everyone, I am currently designing a bandgap reference (BGR) circuit in IBM cms9flp. Using Assura for LVS the circuit is shown to be correct (layout schematic match, and no extraction problems) When I use Calibre the result is Correct again, there are no extraction problems, BUT there is an ERC error. The description of the e
I am using cmos9flp IBM that offers vpnp as forward bias diodes for bandgap design. In the LVS I get an error showing that C is connected to sub! instead of VEE. Has anyone any idea how to overcome this error? D.
I have to design a buffer which buffers 0.6V voltage (which is coming from bandgap ...) to some other block. Any noise/ sudden variation at the output should not affect the input of the buffer. what do I need to consider in my design (not layout), to make sure that this noise doesnt reflect at the input? Thanks
Hello! I designed bandgap voltage reference. In attachement is PSRR jpeg. Tell me please: does this PSRR normal or bad? Exactly what about 0 dB crossing? If it's very bad how correct this without topology and layout change? Maybe capacitance at the Vref node? yes, it is quite normal graph for PSRR. but maybe you can
Hello everybody, I am new to design of BGR, The question is that the selection of diode ration(1:n). Commonly every one prefer 1:8 to achieve good common centroid configuration in layout. But is there any ratio which is leass than 8? Thanks inadvance. bharat
Can anyone elaborate the detailed points to review a bandgap layout.
There will be a layout for a transistor in the PDK for the process and you MUST use that. Then you use multiple transistors for the bandgap. You DON'T do what you have drawn. What is the process? Also 10:1 is a strange ratio - difficult to get a good layout. Powers of 2 are better. 8:1 is good - a 3x3 matrix with the single one in the (...)
How to check the operating point of the start up circuit of the bandgap reference is turn off after the whole circuit is working? (when i ramp my input from 0 to 5V) You can use the writefinal option. See this thread . ... can anyone give me som
A lateral BJT with base width under a micron, is probably only going to be geometry-repeatable when drawn as a self-aligned structure. That means a MOS gate over the base region, a lightly doped (rather than mid-doped) base and a high pinched base resistance. Possibly suitable for a very low bandgap current, but with the gate over base it w
hi all im designing a bandgap reference with two serial bipolars but im stuck at layout. i need to know a technique for implimenting this circuit , i red that diode ratio must be 8:1 but i dont know the reason. if anyone can help me with designing layout for: a)the cascoded current mirror(which consist of pmos) b)the opamp c)diode (...)
Hi, Can anyone comment on the minimum spacing requirement between bandgap reference module layout and DCDC regulators(w.r.t.switching node)module layout in 65um technology to minimize the transmission of noise generated by DCDC ?PowerFETS inside DCDC are well surrounded by double guard is inside a power management IP used in a SoC .
Hi,everybody! I have some problems about bandgap circuit design here. Those are below: 1、The ration of the two transistor area is usually 8 ,not 4 ,16 ,why? 2、Why is the temperature coefficient of Vbe -1.5mv/k to -2.3mv/k?; what is it related to? 3、what type of BJT is ususlly used ?why? 4、What typ
Hi! I design LVDS transmitter. Power supply is 2.5, transistors with thick oxide. layout is standart: 2 nmos switch, 2 pmos switch, bandgap, bandgap based current reference and CMFB. In DC this work good: Vos stable. Vol Voh also. But when modeling transient process there are distortion at the moment of switching. Vos, Voh, Vol go up (...)
start from read book, then with simple case, just for bandgap circuit, opamp etal.
Hello I know that foundry provide pnp model+predifined layout cell. If You propose self pnp layout, provided model can predict it dc performance inaccurate This is important if You are design bandgap ref (for ex) Regards
I have taped out a bandgap circuit and the test results shows that the bandgap is failed. Test reports show that the bandgap drifts about 200mV on one wafer i mean test all dies on one wafer, the voltage drift about 200mV. The bandgap is amp based. the amp is a two stage amp, the first stage is folded-cascode and the (...)
I am not expert in the field but what comes to my mind is : - choosing right components for signal conditioning (16 adc AN from manufacturers is good start point ) - filtering input signal (LPF and bandgap filter) - averaging results on duration of noise frequency period (50 Hz) - right layout - clean power - calibration - in circuit bias
Hi All, I would be very greatful to you if someone can provide me few sample layouts for Magic layout editor. layouts of amplifier, comparator and bandgap etc etc would be a great help. Even if the layout is of any other analog and mixed signal block .. it would not matter as long as magic files (...)
As you know, most bandgap in cmos process is implemented with lateral PNP. The match is good if you get a good layout even the beta is pretty blow about 15~30
I have some trouble in my first design project,bandgap. In layout process,there are some problems: First:PNP.I know the ratio 1:8.But how to draw them.Both the emitter and the base connect to the ground. Second:resistor.How to draw them in precise value or ratio?
The picture is simple bandgap, voltage drop in Q5 and Q6 is Vbe1 and Vbe2 respectively. Q5 and Q6 is replacement of diode. right? Why everybody use PNP instead of diode to make bandgap reference? thanks
For typical interviews, I think some questions relating to the following maybe necessary (1) Understanding of 2-stage Op-Amp design (2) Understanding of current bias and bandgap reference design (3) Understanding of simple inverter transfer function and the operation region w.r.t. each input voltage range. (4) Understanding of layout matching e
Voltage Reference - From Diode To High Precision High Order bandgap Circuits. by Rincon-Mora
hi, about trimming, there are three kinds of trimming technique (1) metal fuse, (2)poly fuse (3)lazer fuse you can choose anyone of them. when test after mass-production, test engineer design a probe card accroding your chip layout and write a C program, The computer run the C program, control the probe card to touch the chip's fuse P
tsmc/ umc or other Fab will provide 5x5 or 10x10um (emitter area) BJT gds layout . but you should know in CMOS no twin/triple_well , only PNP bjt be use beta is small , only use for diode or bandgap cell some high Volt cmos process provide "really Npn or PNP" device . by the way , parastic BJT spice model is simple even corner
Hello Fei, n=8 is a good choice since when you decide to layout the circuit, n=8 will provide better matching of your parasitic bipolars. The main purpose of M1, M2, M3 and M4 is to keep the voltages at nodes X and Y same and also have the same currents in both the branches. For this the Vgs of M1 and M2 must match for this make the W/L
How to layout the lateral PNP inAMI 0.5um Process? I use it for bandgap. Also how to make it recognizable in extraction so that I can do LVS? Thanks
I read that BJT ratio is usally 8:1, 16:1 or 24:1 due to the layout. not 3:1 why ???
as we konw, the bandgap is very important to many analog circuit. If we find the output of a bandgap after tape out differ largely from the output that we get through simulation, what are the main or the most possible reasons? what can we do to get a steady output from this bad bandgap in chip afer tape out? or how can we repair this (...)
Hi all. How do you design a bandgap which takes care of not only temperature but process variation also? What I mean to ask is, is there any specified circuit topology or something like that? Could anyone please throw some light into this? Thanks
Hi, I understand 1:8 layout. 888 818 888 However, how do the best layout look like according to E, C, B (let's say this is PNP and my Collector is connected to Base). Should I make it like the array with all the Emitter face to one side? Or should I flip them so that Emitter always face to outside world? Anyway, it doesn't matter how my lay
Hi ALL, I am designing a bandgap and I want to trim the resistor, can any one advice me to small area resistor trimming techniques ?? Thanks in advance
many designer use N=8 why use N=8 ? -> for layout easy ? why not use N=1 N=4 N=31 N=48 ??
When I simulate a convential bandgap voltage reference circuit by using Hspice, transient analysis is need or not? why? I already had a dc sweep analysis. thank you.
Not sure if it is helpful, but there is a lot of info on bandgaps there.
HI All! Could you give some information that should be considered carefully in bandgap layout (papers or files or books). Thank you very much!
clean power : analog VCC dirty power : digital VCC the bandgap core should be isolated, usually the core including BJTs + OP+current mirror+resistors.
you can layout PNP xsistor in the n-well process for bandgap and you connect collector to GND. Now when you simulate, you have to use diode model in your simulation because you're using PNP as diode anyway (Base and Collector are connected). That's how it's been done. I hope it helps. Adios.
Could anyone give me some information about the bandgap reference use cross-coupled quad of devices?Especially how to calculate the Iout.
bandgap use opamp to stable and pnp to generate
if you design .25um bandgap Vcc=3.3 and 0.18um still vcc=3.3v .. don't need re-design .. but if you use vcc=2.5 or 1.8v --> re-design and if Vcc=1.8 bandgap=1.2xx it is diffcult design you can not cascode MOS (poor PSRR) ..
I can not find this kind of bandgap architecture in books or papers. Who can tell me how it works. Thanks.
Hi~ Can anybody help me this? In my bandgap refernce design, the OPAMP was used to force 2 nodes in identical voltage level. However, in my silicon data, the negative input has ~100mV deviation measured from whole wafer (>100ea dice), but positive input node has very converged voltage appearance and it is close to simualtion result. The bandgap ou