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62 Threads found on edaboard.com: Mismatch And Offset
Hello , I need to calculate W and Wc of the offset couler by an input of Zoe Zoo s b Er i have tried writing using SOCLIN calculator but it doest allow me this input all of them without changing the previos input parameters, input: Er=2.32 b=3.3 S=0.03788 output (of the book) Wc=0.2789697 W=1.220193 the photos of the books example (...)
A well designed amplifier -should- have trivial Vio variation with PVT and one which has any sort of autozero function may display no measurable Vio even with gross VT scatter. You need mismatch statistics enabled (by you) and modeled (by foundry, or roll your own) to see realism in Vio. The PDK docs ought to tell you the series of motions (...)
Using larger ( by maintaning W/L ratio) will reduce the larger MOS area has less mismatch..
If you have mismatch (Avt) parameters from the foundry/fab you can calculate worst case offset values for adjacent transistors, depending on their size. Or you can run a Monte Carlo analysis if you have the corresponding mismatch set.
Gm has a peak and this is usually a little bit below VT. Which direction you'd go, depends on where you started. Increasing gm helps kill the backend offset contribution, whether it improves matching significantly in the diff pair itself I don't think is the issue. I rarely if ever see mismatch data besides VT-match, and (...)
I am simulating a simple one stage differential amplifier with Spectre, and trying to see the effect on the offset due to the mismatch of just some transistors. I am able to perform mismatch simulation for all the instances I am able to perform mismatch simulation excluding some instances (i get (...)
You run a Monte-Carlo analysis and look for the point where the current in the two devices is equal. It will only be approximate - it will take account of Vt and some other mismatch parameters but will not account for speed differences between the two halves. Keith. - - - Updated - - - The way to do it dyn
In first approximation, the loop gain ALG is responsible for the inaccuracy = nonlinearity: inaccuracy = 1/ALG = |AFB| / AOL In your case AFB = -10 ≙ -20dB AOL(LM358,typ) = 100dB inaccuracy = 20dB - 100dB = -80dB ≙ 0.01% = 100ppm The (amplified) offse
It depends on your offset and noise requirement. The pmos loading pair mismatch and noise will be reduced by gmL/gmI. gmL is gm of loading PMOS. gmI is gm of input NMOS.
I have opamp (see attached figure) I am doing its Montecarlo simulation in cadence spectre. This is low power application so the current in the branches are about 25nA. The problem is that the currents are matched relatively good like only a 4 to 5nA of difference in the branches. But the node voltages are very different. for eg. for the bottom cur
Dear friends, As far as I am new in using cadence, I will be grateful if any of you would kindly give me any good tutorial or an example of how to run monte carlo analysis to measure comparator offset due to the mismatch of input transistors? or draw statistical diagrams. Unfortunately the cadence help is general without any example and I (...)
When I plotted histogram of Vth of one of the transistors,It is showing a standard deviation of 6.5m and mean of 283m.Does this mean Vth mismatch(and hence the offset of comparator) will be around 19.5mV(3*6.5)??
Hi all, I'm using sense amplifier based comparator in my ADC.please post some reading materials explaining various aspects (and design)of comparator like dynamic offset,mismatch,parasitics,hysteresis etc., This is the
With 400mV offset, I would rerun that particular MC run and verify circuit functionality. I highly doubt that result was due to offset. The primary culprit for high offset is the first amplifying state, ie the input pair (You need a high Gm one, and large area of course!). This is followed by having high (...)
You have to model mismatch between the typically matched transistors (like the input transistors of input differential pair) to see an offset at the output. I would do a monte-carlo simulation with mismatch as the parameter and ensure that the mean+(3*standard deviation) value of offset is (...)
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 overall offset is a combination of the input-referred offset of the input pair and PMOS mirror: Vos = Vos(input pair) + Vos(pmos mirror) = Avtn / sqrt(Wn*Ln) + gmp*(Avtn/sqrt(Wp*Lp) / gmn gmp*(Avtn/sqrt(Wp*Lp) is the current mismatch (gm*delta_vth) of the PMOS mirror, dividing by the input gm converts the (...)
i think it's really hard to design precision CMOS bandgap due to mismatch and offset of MOSFETs are more serious than BJTs. there are some published papers focusing in this, but dont know whether it can be really used in chips for production.
The bandgap voltage spread is defined by the offset voltage spread of the control amplifier and the current mismatch of T4/T5. The used bipolars could have an impact depending on the amount of voltage drop of the internal emitter resistance. That resistor re*(1-1/12) have to be compared to the 200 ohm resistor (...)
When I simulate the comparator offset, what percentage of input diff pair mismatch should be set? and what is the typical value of offset when using TSMC 0.18um technology? Thanks!