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.

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51 views

FRR Measurement in Oscilloscope

I have a GDS-20174A digital oscilloscope. I am trying to measure the delay between two BNC cables using a square pulse of 2V with an offset of 1 V using the oscilloscope. I am using the FRR ...
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42 views

FRR Measurement

When I try to measure the FRR (time delay in the rising edge of two pulses) between two channels of a GES-2074A GW-Instek digital oscilloscope, it varies depending on the time resolution. First, I ...
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62 views

How does risetime affect transmissionline effects?

How do rise and fall times affect reflection in a transmission line? Reflection will occur with shorter lengths as rise times becomes shorter, does this mean risetime effects the wavelength of a ...
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64 views

Rise time for 2 MHz SPI clock signal driven by an Arduino Micro

Could someone tell me what a typical rise time would be for a 2 MHz SPI clock signal driven by an Arduino Micro (ATmega32U4), off the SCK pin? An actual measurement would be preferable, but I do not ...
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31 views

Is there a difference between rise and fall time and modulation frequency

I was wondering if there was a difference between modulation frequency and rise and fall times of a laser diode or LED? If a laser had a modulation frequency of 100MHz would that be the same as a rise ...
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29 views

TLC5926IPWPR Clock width

I'm using the TLC5926IPWPR in a design. It uses an SPI interface. The TLC5926IPWPR chip is on a separate PCB than the MCU that is controlling it. The Clock and SDO pin must go through a cable about a ...
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2answers
82 views

How to increase voltage rise time for micro controller?

I am working with a micro controller which has this written in its data sheet: "A step increase in supply voltage of 300 mV or more, with rise time of 300 ms or less, within the valid supply range, ...
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1answer
310 views

High voltage nanosecond pulse generator

I am trying to build a PCB based pulse generator that can produce a pulse with a width of about 100 ns and 500V-1000V peak amplitude to a 50 ohm resistive load. I will use the circuit for burst pulse ...
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60 views

How much slower does a photodiode become in photovoltaic mode?

Take for example this photodiode, the main differences between using it in photovoltaic and photoconductive mode is the rise time and the Dark Current, aren't they?. I know exactly how the Dark ...
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53 views

Lossless Transmission Line Length vs Rise Time

I am trying to answer the question - Does a signal's rise time increase with the length of a lossless transmission line? - using LTspice simulation. Some references say that lossless transmission line ...
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46 views

Generate ultrashort rise times with photoconductive switch or photodiode

I am trying to produce voltage pulses with very short rise time (<15 ps), medium width (20 ns) and amplitudes up to 15 V. As a promising candidate I selected photoconductive switches and ultrafast ...
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63 views

Constant DC Load Stability and Bandwidth slewrate

For this circuit, how do I know if the rise edge was limited by slew rate or bandwidth? What's the effect of R2 and C2 on bandwidth? -3db of this circuit in simulation is 649 kHz, I know in ...
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113 views

What does t2-t1 represents in the expression t2-t1 = RC*ln|9|?

And how do I find t2-t1 with an oscilloscope? I was given the following problem, I derived the expression in the title of the question and I need to use the oscilloscope to find t2-t1... Resistors ...
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51 views

minimum readable rise/fall times in an oscilloscope

How can I calculate minimum readable rise/fall times of a signal in an oscilloscope (from practical point of view)? Does it depend just to bandwidth and sampling rate of oscilloscope? regards
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174 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 ...
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914 views

How to calculate the rise time and fall time of a flip-flop?

This is an effort to find the rise and fall time of the following circuit. I have calculated the rise time and requesting confirmation from expert’s end. There are some assumed values like trace ...
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221 views

Rising edge of a pulse or one complete pulse needed for 1 step in Stepper motor?

I'm trying to make a step counter using Hall effect sensor implanted near the rotor of a common hybrid-synchronous(1.8° in full step) stepper motor, and I'm confused as I'm not able to figure out when ...
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108 views

Is the rise time of the output of a logic IC or optocoupler independent of the rise time of the input?

Is the rise time of the output of a logic IC (e.g. flip-flop or inverter) or optocoupler independent or dependent on the rise time of the input? If the answer is dependent, are there any other ...
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1answer
373 views

No Feasible Entries for Subprogram “rising_edge”

It's my first time coding in VHDL and I ran to some problem I have absolutely no idea how to solve. When I try to compile my code in modelsim it gives me "No Feasible Entries for Subprogram ...
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298 views

long stub length rs485

TI recommends their low-data rate transceivers to cope with long stub lengths for RS485 networks -- eg Page 3 of http://www.ti.com/lit/an/slla272c/slla272c.pdf I want to use an isolated interface, so ...
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1answer
723 views

Transistor - rise time for switching applications

I've been looking at basic theory of Bipolar Junction Transistor. In switching application design, in order to have a saturated transistor it is often required to find an appropriate value of the ...
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2answers
898 views

Gain and Rise Time with Transimpedance Amplifier Circuit

I'm working with a transimpedance amplifier circuit using a Silicon Photomultiplier. The reference circuit is shown below: simulate this circuit – Schematic created using CircuitLab This ...
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4answers
3k 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,...
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578 views

RC time constant of amplifier circuit

I'm trying to determine the effect of how changing the capacitance will alter the rise time of the output voltage in the following circuit: simulate this circuit – Schematic created using ...
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5answers
439 views

How to equalise highly asymmetrical rise and fall times?

This question is kinda similar to highly-asymmetrical-rise-and-fall-times, but I think that the data sheet is already suggesting that I'm at the optimum design. Resistor changes were the answer to ...
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1answer
506 views

Photo diode TIA

here i have designed a TIA circuit with the suitable values for the feedback resistance and feedback capacitance and using the FDS100, to achieve a bandwidth around 43 MHz, the simulation is running ...
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1answer
59 views

Need help understanding rise time parameter in nc7wz04p6x datasheet

I am looking at the datasheet of nc7wz04 UHS dual inverter. The propagation delay specified is 2.3ns. The rise time/ fall time of input pulse in the fig 6 is 3ns. But in recommended operating ...
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1answer
148 views

Pen-type barcode scanner

I am designing a pen-type barcode scanner (1D) which is operated by user, which means that the speed at which the scanner moves is random. Even worse is that it gets stuck sometimes, so the signal ...
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1answer
278 views

Slow rise time on MOSFET

I'm doing this project, where i control the speed of a motor with a 0-3.3 V PWM signal from a microcontroller. In the test setup i use a function generator (Digilent Analog Discovery). I would like ...
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1answer
574 views

How to determine rise time from a datasheet?

I am trying to determine the rise time for a component in my circuit. I am unsure if my current method is correct and could use some verification. I would love help in the general case as well. Case ...
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2answers
167 views

What is the current rise time of a discharging capacitor?

There are many questions about capacitor discharge rise time here on the electrical engineering board but all involve transistors or are oscillating circuits rather than a purely shorted out capacitor....
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1k 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 ...
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1k 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 ...
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224 views

Are overdamped rise waveforms really “curvier”? Or is that just time scale?

Do the rising waveforms for overdamped circuits of different \$\zeta >= 1\$ actually have a different "curviness"? Or does it just look that way because they're all shown on the same time scale? ...
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2k 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 ...
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1k views

LTspice default rising/falling times of pulse edges

Above is how I set up a pulse in LTspice. When I set the rising and falling edges as zero or if I do not register any value, in that case LTspice automatically sets the rising and falling edge ...
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82 views

Rise/Fall time of GP Pins

Are rise/fall times typically affected by the clock speed. That is if I have a AVR at 16 MHz will it have a different rise/fall time than the same AVR at 32kHz?
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1answer
461 views

Reverse biased photodiode gain resistor selection

I have a reverse biased photodiode as shown below. where R1 = 100kΩ. The output is quite low around 50mV. I would like to replace R1 with 1MΩ to get 10x the output. My concern is, if it will have ...
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130 views

When does an RC Transient period end?

I have struggled with this question and read many articles and watched youtube videos but to no avail. For this circuit the time constant or "Tau" is 80 micro Farads (or$$80*10^-6$$) My issue lies ...
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17k views

LTSPICE - How to create PWM with rise time

A simple PWM circuit is simple to create using LTSPICE, such as: ...
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1answer
115 views

CMOS Gate and Coupling Noise from Loose Wires

I am currently working on this small circuit which as you can see, has to level shift a 3.3v 1Hz PPS signal into a 5v pulse. Everything is marvelous when I measure the level shifted pulse with the ...
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3answers
724 views

RF FETs - how exactly are they different from regular FETs?

I've browsed through DigiKey and there are these RF FETs. Are they for final stage amplification? Say you have an opamp that doesn't go for the final desired voltage, so one uses these FETs as Common ...
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156 views

Impedance discontinuity problem at transmission line?

I am confused about how the waveform will be to the left of discontinuity. Please help me understand it better. Here is my understanding: When the unit step hits the inductive discontinuity, at the ...
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900 views

Computing Rise Time on SPI Bus

I am designing a circuit board that has an SPI bus with 32 slaves. I plan to drive the bus at 8 MHz. Another individual on this site commented on a previous post of mine that the total capacitance ...
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2answers
4k views

Why is CMOS fall time faster than rise time?

I've just started a computer architecture class, and the slides from a lecture says that the reason why fall time is faster than rise time is that the NMOS electrons have more mobility than PMOS which ...
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90 views

Two cables, same resistance, different lengths, speed of current transfer

If I have two cables, with different size, but in total the same resistance, what will be the speed of the current transfer( how much time will it take the voltage to appear at the end of the cable). ...
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352 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 ...
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219 views

Improve DAC Pulse Rise/Fall Time

I have an older NI DAQ (PCI-6251) which comes equip with a bunch of ADC's, two DAC's and a hand full of DIO ports. I need to output a pulse of variable width, amplitude and DC offset which the DAQ ...
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556 views

Balancing Rise and fall times at input and output in CMOS Design

How do I make sure that my rise and fall times are balanced between input and output in a CMOS design?
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2k views

How does the improved transistor astable multivibrator work?

This is an astable multivibrator circuit. Assuming that TR2 is initially on, the right pin of C2 is grounded and since C2 isn't charged, the left pin of it is also at 0V. Now, Out 2 is low. C2 is ...