Questions tagged [rise-time]
Anything related to the rise time of a signal. The rise time is a parameter used to characterize abrupt transitions in a signal waveform. It is usually defined as the time needed by the signal to go from the 10% to the 90% of the level it attains at the end of the transition.
116
questions
10
votes
4
answers
9k
views
How is rise time related to bandwidth of the signal?
Say, I want to limit the rise time of my digital signal edges to avoid dealing with transmission line effects.
How do I determine the maximum frequency of harmonics in my signal knowing that my rise ...
- 5,571
8
votes
2
answers
5k
views
How to determine if a signal path needs to be treated as a transmission line?
I remember reading this somewhere but cannot find the ratio of the rise time vs. the propagation time (i.e. the trace length?) of a signal when transmission line effects come into effect?
For example ...
- 851
8
votes
2
answers
6k
views
How to control rise time of output of LTSpice's Voltage Controlled Switch?
I have a RC delay circuit as input into a Voltage Controlled Switch in LTSpice. It's working the way I want, except I can't figure out how to shorten the rise time of the signal that emerges from the ...
- 353
8
votes
1
answer
1k
views
Do long transmission lines degrade rise/fall times, and if so, by what mechanism?
I remember someone telling me long ago that if a voltage step is sent down a transmission line, the step will become smeared as it travels down the line, and the rise time will become degraded. I'm ...
- 57.6k
8
votes
1
answer
5k
views
How to determine BJT switching time
Is there some standard way to get information about BJT (Bipolar Junction Transistor) rise and fall times (the high power ones) ? In essence a IGBT is a BJT being driven by a FET, so there should be ...
- 1,022
8
votes
1
answer
360
views
How do I calculate rise times for a push pull GPIO with load with hand calculations?
simulate this circuit – Schematic created using CircuitLab
This is a simplified example of a push pull GPIO found in most microprocessors, with a load attached.
Using the capacitance and ...
- 84.8k
7
votes
4
answers
12k
views
Driving a MOSFET with fastest rise time possible
I'm working a circuit to send very short pulses to a load, with the requirement that the pulses have the fastest rise time possible (~10ns or less).
I've picked out a driver that has a fast rise time,...
- 175
6
votes
2
answers
2k
views
Real rise time with oscilloscope and probe
I'm still a bit new to this domain, just wondering if the rise time of a probe and the oscilloscope itself have to be substracted to the measure in order to recover the real measured rise time?
Let's ...
- 177
6
votes
2
answers
793
views
How come you cannot determine the capacitance of a MOSFET gate based on the other supplied values on the datasheet?
Conjecture
If it's the case that
$$
Cg = {Qg \over Vg}
$$
It must be the case that
$$
(Ciss + Coss + Crss)Vg = Qgon
$$
But it turns out that it is not. I don't understand what I'm missing.
I ...
- 603
6
votes
1
answer
3k
views
Is this measured rise time inaccurate because of limited oscilloscope bandwidth?
I don't have an LCR meter and wanted to learn how to use a fast edge pulse generator and an oscilloscope to do capacitance measurements as an academic exercise.
In W2AEW's videos, he builds a simple ...
- 34.3k
6
votes
1
answer
457
views
Why is BJT NAND rise time so high?
I'm testing a few different circuits for basic gates, made in DTL (Diode-Transistor Logic). One of the more popular layouts for NAND seems to be:
simulate this circuit – Schematic created using ...
- 354
5
votes
1
answer
1k
views
LTspice capacitor bug?
I know that capacitor slows the rise of voltage, but why is this not happening in the LTspice simulation?
I got the input voltage at the output instantly.
- 107
5
votes
4
answers
5k
views
Root Sum Square
Can anyone in a simple way explain why this formula works. It is the Root Sum of Squares where you square your values then add together then take the square root. It seems to be used quite a lot in ...
- 167
5
votes
1
answer
265
views
Unexpected voltage spikes at output of PFET on falling edge
I have the circuit shown below:
I want this circuit to switch between 2.5V and 3.6V at the drain of the PFET when I input a square wave into the gate of the PFET.
I would expect that this circuit ...
5
votes
2
answers
875
views
Square wave generator has nigh-useless output
I have a system that was designed for testing digital components. I have a device in the system which is used for generation and acquisition of digital signals. Now, I will happily admit to not ...
- 476