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73 Threads found on edaboard.com: Ptat Circuit
Hi, In band-gap reference circuit.Why there is 1:n ration of BJT? Regards Shrikant In order to create ptat current source.This current will be used to compensate VBE vs. Temp value.( remember that VBE drops down approx. -2mV/deg )
I doubt that a fully differentially amplifier is right in this place. Unfortunately the circuit can't be analyzed without knowing the ptat/CTAT output characteristic. To work in the shown circuit, ptat and CTAT output node must be bidirectional current sources but they most likely aren't.
Please refer to the attached circuit. 117083 It's obvious that MP1-3, R1&R2, Q1&Q2 work as a bandgap reference circuit itself. With appropriate combination of the ptat current and the CTAT Veb voltage drop, a desire bandgap voltage reference can be produced. However, what about the middle part? It seems like there's a
Hai In 65nm technology if we have to design current references(4mA, 10mA---) what type of circuit we have to choose either a simple betamultipler or a ptat from a BANDGAP reference. Thank you satya
Hi All, I am using the circuit from this paper in designing a ptat circuit "A Novel Wide-Temperature-Range, 3.9 ppm/C CMOS Bandgap Reference circuit",by changing the input transistor of opamp from MOSFET to BJT. This is the ptat circuit and the detailed schematic of Opamp. Startup (...)
You have a ptat voltage across R1. Vptat = (KT/q)ln(m) This would fix the current in the PMOS current mirrors as a ptat current, Iptat = Vptat/R1 Your Output Voltage Vref = (IptatR2) + VBE,q3 Now adjust R2 to get Vref as constant across
Hi all, I am designing a bandgap reference circuit. Attached is my ptat with its opamp structure. It is a folded cascode one. However, when I simulated the circuit, the output current shows the oscillation. Could anybody advise how can I make the frequency compensation of this circuit? I do not know how to deal with this (...)
91050 Hi good day, If someone could please explain to me this circuitry working principle. I have search many books and articles but havent really find any answer to my question. I understand how the bandgap reference circuit works and the principle. I can understand the typical bandgap reference circuit. But I
Hi all, I need to implement a temperature sensor based on the circuit shown in the attached schematic. Unfortunately, the current flowing thru M1/M2 is not ptat. So then how can I implement a temperature sensor based on this architecture? Any guidance will be helpful. Thanks.
dear all I have designed a biasing reference current by adding ptat and CTAT currents together. the result is a biasing current with small temperature coefficient. However, since both the PTA and CTAT has R in their equations, the total current still depending on the process variation. not like the bandgap reference voltage where no R in 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 algorithm
Hi All, I need to design a voltage reference circuit 1. The output should be a constant voltage below room temperature 2. Output should act like a ptat voltage above room temperature. This should be a single voltage reference satisfying both conditions. Please share your ideas.
hi all, i got PATA current from Razavi at chapter there is no more detailed start-up for this circuit. whether the circuit needn't start-up circuit? if start-up circuit must have, can anyone recommend or what document i can r
The attachment is a CTAT and ptat current generator circuit for low voltage operation. My understanding is that as temperature increases, the Vbe(Q1) decreases and Id5 decreases since Vbe / R2 has decreases. This generates the CTAT current. Combination of the CTAT and ptat currents makes a ZTAT current which is quite good. However, my (...)
i would agree with you...but the formula is derived exactly starting from this formula v_R=delta_vgs and ends up in this ln form .... theory on ptat current source confuses me obviously :P
razavi, chapter "bandgap reference",section ptat, or just google "ptat"
Hi palmeiras, here are some new outcomes from my side: 1) When you wrote: “the resistor leading to a reduction in VGS2=VGS1”. Do you mean VGS2 minus VGS1, right? Because VGS1 is always different from VGS2, never equal. Sorry, this was a typo: Of course it must be Vgs1=Vgs2+Ids2*Rs=Vgo2 (referred to ground). A last thing:
... which one should be chosen when desing a circut? what is the rule There's no rule; this depends on the circuit's requirement, as Jgk explained above. Occasionally I use a ptat source to counteract the speed deterioration at high temperatures (due to mobility degradation).
How to simulate a ptat circuit? Run a DC analysis and sweep the temperature. can someone show me how to set the parameter of the component for ptat circuit? Your question isn't clear to me: Which parameter of which component? How is your circuit? Schematic, Verilog-A, AHDL, functi
In bandgap, the ptat current is obtained by the delta_Vbe/R circuit. The implicit assumption is that the same current flows through both transistors! In Bandgap A, the opamp offset and mismatch will contribute to the current difference. In Bandgap B, if we ignore R2/R3 for the time being, the current difference depends only on the opamp offset m