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36 Threads found on edaboard.com: Inverter Rise Time
Yes, they can - especially if you have nonuniform taper progression. The rise / fall edge time asymmetry can stack up (and is very loading-detail-sensitive; slow edges are where you convert voltage noise (as can be seen on your top trace) to time noise (jitter)). I once had to redo a chip-scale clock tree (on a 40Kgate ASIC done by Spectre (...)
Hi guys,how to find the input capacitance of inverter chain (inverter connected in series) using cadence? I need to find input capacitance so that I can size each inverter stage using logic effort.I am referring to this slide page86 formula.
For a triangle waveform to produce the same result as a DC hysteresis sweep, the delay of the path in question must be << the ramp time -through the region of interest- (e.g. the linear window of an inverter chain). A 1uS total rise time and a 10nS prop delay will give you 1%-ish error if the whole range is linear, (...)
In Clock buffers rise & fall time are balanced. So while designing clock buffer Beta ratio should be chosen such that clock buffer/inverter rise & fall time should be same.
hi, 2:1 ratio is done ,in order to make sure that rise and fall time of the output are same. if we increase the width values , the driving strength of the inverter (current) increases .
please attach your simulation or experimental waveforms of current and voltage. It has be noted that this is not a new configuration. It just a hybrid implementation of a 2-level H-bridge inverter and a modular multilevel inverter as it can be conceived form schematic. P.S please delete the filter; connect the output to a resistor, and report requ
Why is it required that the NMOS and PMOS transistors at the inverter have different W/L ratios?
Hi I tried using this formula to calculate rise and fall time in calculator , but the expression fails.Could anyone help me? risetime(VT("/OUTPUT") M1 t M2 t 10 90) Thanks BB
I'm designing a CMOS inverter circuit. Right side graph is output voltage. My question is why is there a peaking at 1us, 2us, ...(yellow mark) and how can i remove it? 79966
Hi all. Can you tell me why we should equate the rise time and fall time of a standard cell ? Like a inverter, we usually draw a pMos 2 times wider than nMos to ensure the rise time is matching the fall time. Thanks!
I designed an inverter in TSMC 0.18um process. NMOS is 900nm/200nm X2. it can contain 2 contacts. and PMOS is 2.7um/200nm X2. So the width of PMOS is three time than NMOS. this inverter drive 10fF capacitor and an another inverter. . rise time and fall time are equal (...)
One "trick" that I have seen have been to connect an inductor inbetween the MOSFET-switches. How do you suggest ? and what value? My inverter is using center tap Transformer with 24V dc and two plates of IRFP 250 Mosfets ( Three Parralal) in each plate) . Usualy all blow when inverter is running and
That is the goal. But in reality buffers and inverter rarely have the same rise and fall time as it depends on the capacitive load of the clock tree its driving and the drive strength of the CLKBUF/CLKINV. So instead of of using buffers/inverters with the same rise and fall time. CTS tries (...)
Hi all , I need clarification on hold time of TSPC(+ve edge per my perception hold time for D=1 is zero(if we assume zero rise and fall times) and for D=1 it is delay of second inverter minus delay of first it
Is this really needed ? Would this really work ? - A single transistor in a current source configuration and for the present signal polarity an inverter stage should basically do. - The 10 k driver load resistance/Q3 gate capacitance sets a rise-time in a ?s order of magnitude, so you can't achieve 10 MHz. 115K can hopefully work.
you could use a gigabit logic inverter gate, capacitively couple the output to a short circuited transmission line. The gate provides a quick rise time, and the short circuited transmission line makes the pulse width narrow. Should work for a 3 Ghz mixer.
Because of the (W/L) which is the width over the length factor. You are changing P MOS width rite? But the Kr changes. It will change the voltage transfer characteristic of the inverter. From there only,you can see the fall time and rise time.
Please help to find an best answer for following question: Can I use inverter as level shifter? If no why?
Yes. For a given rise time, lower signal swing means slower slew (V/ns) which means the inverter input transistors' threshold voltages will take longer to hit, and that the input capacitance will take longer to charge.
hi i m going to design a cell library at 0.18u technology. i want to know how to design a unit load. i designed the balanced inverter as unit load. but the rise and fall time at the output are not same. so i changed the width of PMOS to make them equal. now time is equal but switching Vth is not 1/2 Vdd. pls tell me the (...)
Hi All, Can someone tell me the difference between a Normal Buffer and a clock Buffer. Also I would like to know the difference between Normal inverter and a clock inverter. Any materials regarding the same would be very helpful. Thanks in advance Chethan
hi, i wonder if anyone can help me with this "inverter delay measurement" problem i have. Normally, textbooks define inverter propagation delay to be = RCln(2), which is the time interval between 50% change in input to 50% output change (CMIIW). Apparently, this formula is only good for very small input rise/fall (...)
To get equal rise time and fall time, size the nmos and pmos inverters in the opposite ratio of their mobilities. (W/L)n/(W/L)p = (mobility)p / (mobility)n
in my opinion,normally the propagation delay and the rise/fall time are two parameters that have no directly relation, the propagation delay is for speed, while the rise/fall time is for signal quality, that the propagation delay is bad does not mean the rise/fall time is bad. but for (...)
If your circuit run at high frequency, and the die size and power consumption must be optimized, it had better that let the rise time is equal to the fall time. "Size PMOS 2 or 3 times larger than NMOS in the inverter" is better, is not must.
i only know inverter chains with resistors to generate pulses and delays
One way is to lower the supply voltage, it gives quadratic power savings, ideally. Sizing transistors also matters, for example of an inverter, it's suggested that the output transition slope is much longer than the input rise/fall time, to reduce static current dissipation. But again, if we look at the global picture, making them (...)
by source/sink current calibration or use current mirror to bias the output inverter stage
Can anybody give me the complete derivation of rise and fall time equations of a cmos inverter?
Hi Both n-mos and p-mos widths are minimum widths(that means we cannot folde it to decrease the rise time ) then To maintain the equal rise time and fall time to the inverter What are the steps your going to tack ? Thanks Sivakumar
hi all, Please tell me how to calculate current in PMOS and NMOS of CMOS inverter. the current depend on the load the inverter going to drive according to the formula I= c* dv/dt I= current c= outout load dv/dt= how fast the output voltage need to rise in a certain time, this depend on the speed requirement.
In other way, rise and fall time of an inverter depends on the charging and discharging of the o/p capacitor. so to get equal rise n fall time we require to made charging and discharging currents equal ... so the charging current depends on the mobility and w/l of the PMOS so we require to make larger (...)
build your inverter and dummy load inverter, add test step source, run trasient simulation, measure for rise/fall time.
Hi, In silicon, Mobility of electrons is around 3 times faster than holes. If you take an inverter, fall time is quick and rise time is more. In order to overcome this problem, Pmos is usually made twice that of nmos. That is why they say NMOS is faster than PMOS.
The NAND gate has two sereis NMOS transistors and two parallel PMOS transistors. So you cannot always obtain fall time= rise time. However, if for an inverter the (W/L) of the NMOS is (W/L)n and that for the PMOS is (W/L)p for Fall time = rise time. For the worst case (...)
I build simulation model of an sigma delta modulator (analog input digital output) in order to control transistors in 3phase full bridge resonant inverter. In negative feedback loop I have 1bit D/A converter and it gives +-5V. Reference voltage is 5V*sin(2*pi*50Hz*time). I couldn't rise this voltage at 220V because of op amp input is max (...)