Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [thd]

13 questions
4
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1 answer

How to extract ENOB from LTSpice simulation and see the effects of oversampling?

I have a fully differential instrumentation amplifier circuit with a gain of 536 to map a 3mVpp signal (centred around 1.65V) to +/-1.6V, as shown here. My signal bandwidth is 250Hz, and I would like to use a 12bit differential ADC (stm32g491) with…
davidanderle
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4
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1 answer

High THD in an Active Power Correction Circuit

I'm asked to design a 30W power factor corrector for "dimmable" LED drivers. Here are the most crucial requirements: THD (ITHD - THD of the line input current) should never exceed 10% PF should be at least 0.91 for PLED ≥ 10W I have designed one…
Rohat Kılıç
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3
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0 answers

Why does the current THD increase and voltage THD decrease when increasing the inverter switching frequency?

I have a three phase inverter model and I am investigating the effects of an increased switching frequency for pre-defined LC filter parameters. It is a simple MATLAB Simulink model: DC source, inverter, LC filter and constant value resistive…
mikebuba
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2
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2 answers

Generating and measuring a sine wave with THD below -80dB

For an experiment I need to generate a sine wave which has a THD below -80dB. I would like to do that using a band-pass filter connected to a function generator because the output of the function generator does not have a THD below -80dB. I found…
Mantabit
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2
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2 answers

DAC "aliasing" of harmonics

While reading articles and application notes regarding DACs and their output spectrum, I stumbled across aliasing of higher harmonics to the first Nyquist band. For example, when generating a single test tone with a DAC, harmonics of the fundemental…
t_nogic
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1
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1 answer

Designing bandpass filter for audio amplifier

I am a 3rd year engineering student currently working on a project where I need to basically make an ultrasensitive metal detector. Basically, I need to create an alternating magnetic field by connecting an audio amplifier (which is also connected…
M.K. Saunders
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2 answers

How to reduce THD of amplifier circuit

I am pretty new to designing amplifiers, but I have been playing with LTSpice and came up with a schematic, however I am not sure how to reduce the THD of the circuit. For 1kHz, I get the following from SPICE Fourier components of V(out) DC…
Boris_bulletdodger
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1
vote
1 answer

Accuracy when measuring THD with LT Spice for AB Audio Amp

I've designed and built my own AB class audio amplifier circuit. I designed it to have as low THD as possible, using LT Spice to run my simulations with the .four command, so I created a bunch of circuits and picked the one with the lowest THD. I…
fcoppede
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2 answers

What causes the large THD increase measured after the output resistor in this op-amp stage?

I'm designing an audio mixer and took good care to create a relatively low THD signal path. At the final output stage I'm measuring a a THD of 0.06%, (10 Vpp, sine @ 1 kHz.) This is measured directly at the op-amp output. After that I added a…
Matt
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1 answer

Reason for frequency steps shown in Simulink FFT analysis tool

While using the FFT in Simulink tool, I have observed that if more number of cycles are selected then frequency steps in which harmonics percentage is shown is also divided accordingly. For example: Number of cycles = 4 , frequency steps =…
Shubham Dhiman
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1 answer

How to calculate THD using only the first harmonic?

How can I calculate THD using only the first harmonic? How can I implement in C code DFT voltage formula in order to calculate THD?
Јелена Продановић
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Relation between THD and spectral leakage or number of samples

So I'm studying data acquisition and on the lab had to perform an experiment involving sampling a sinusoidal signal of frequency 1100 Hz, 70 samples and sampling frequency 22000 Hz. Now I can clearly see that I'll have spectral leakage in this case…
Granger Obliviate
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2 answers

Waveform distortion with high ohm resistor

I have a problem that waveform distorted after adding high ohm resistor, (second figure shows that resistor voltage which doesn't follow of input pulse (yellow). So I added Darlington pair right after 500k resistor node to avoid distortion. But…
shortcircuits
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