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30 Threads found on edaboard.com: Inverter Rise Time
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 (...)
Normally in inverter circuits mosfets fail when another phase is connected accidently by electricians to the output of an inverter .This leads to all mosfets connected in parrelal in both half bridge to Blow. Normal overload protection circuit of the inverter don't work under these conditions. Some manufacturers claim as their (...)
Hi, I have this doubt, that to maintain the duty cycle we need all the buffers and inverters to be having the same rise and fall time. Am I right ? Please explain. -Pavan
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 (...)
it is often said in the inverter PMOS should be sized 2 or 3 times larger than NMOS, because PMOS has low mobility.----the inverter threshold voltage can be shifted to the middle, and the inverter is more symmetrical in terms of transition times, right? In my circuit, when I size the PMOS and NMOS the (...)
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.
Hi Prasad! The drain current of a mosfet is proportional to mobility and the ratio w/l. Electron mobility is typically 3-4 times that of a hole. So to have comparable drive power, the sizing (in an inverter) is done such that the lengths are the same, but the width of PMOS is 3-4 times that of NMOS. Hope it is clear now. Giri
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 (...)