How Does a Capacitor Introduce Phase Delay in a Circuit?

In summary: When you are using the term "delay" - which signals do you have in mind? Such a delay is the delay between two signals (voltage and/or current) resp. the corresponding phases of these signals, in time. When you remember your own definitions, you will know what you have to measure/simulate.When you are using the term "delay" - which signals do you have in mind?You are asking about the delay between voltage and current signals, right? If so, then the delay is the time it takes for the voltage to go from one phase to the next. This delay is always the same for signals that are in phase. In summary, you
  • #1
PhysicsTest
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TL;DR Summary
Understanding the phase delay
I simulated the below circuit to capture the phase delay between input voltage and output current in LTSpice
1689755433868.png

How do i measure the phase delay introduced due to capacitor?
1689755562602.png
 

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  • #2
The rule is that currents in a series circuit are ALWAYS in phase. So I'll ask you what can you conclude from that rule and the circuit you have drawn.
 
  • #3
When you are using the term "delay" - which signals do you have in mind? Such a delay is the delay between two signals (voltage and/or current) resp. the corresponding phases of these signals,
When you remember your own definitions, you will know what you have to measure/simulate.
 
  • #4
This would normally be done with sine waves, not square waves. This is because the phase delay depends on the signal frequency. A pulse waveform contains many frequencies. It still can have a phase shift, but it's complicated. So sine waves, which are a single frequency, often swept through a range to make a frequency response (Bode) plot, is what most EEs use.

In any case, you need to specify the conditions, like the input waveform, for phase delay to make sense.
 
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  • #5
PhysicsTest said:
TL;DR Summary: Understanding the phase delay

I simulated the below circuit to capture the phase delay between input voltage and output current in LTSpice
It looks like you are using a Transient Analysis -- that is not the type of analysis that you should use to see the Frequency Domain characteristics of a circuit. Have a look at this article, and let us know what a better SPICE analysis mode would be... :smile:

https://techweb.rohm.com/know-how/simulation/7916/
 
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  • #6
I am analyzing the circuit and will come up with the exact problem i am facing.
 
  • #7
PhysicsTest said:
I am analyzing the circuit and will come up with the exact problem i am facing.

A square wave will charge a capacitor up as soon as it is applied because it is similar to direct current.

Are you wanting to test the time constant, tau, as it is charging?
 
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  • #8
osilmag said:
A square wave will charge a capacitor up as soon as it is applied
More accurately, a square wave will start to charge up a capacitor with the initial application of the first pulse. Subsequent pulses alternately start to discharge it and recharge it... (see the OP's transient SPICE simulation):

1690549470447.png
 
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  • #9
Ok
 
  • #10
As has been noted the term phase delay (better called phase lag) is defined as the response to a particular frequency sine wave. So your question is not well formulated. Please try again.
 
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What is phase delay in a circuit?

Phase delay in a circuit refers to the time difference between the input and output signals of a circuit. It is caused by the reactive components in the circuit, such as capacitors and inductors, which store and release energy at different rates.

How is phase delay measured?

Phase delay is measured in degrees or radians. It can be calculated by dividing the time delay by the period of the input signal and multiplying by 360 degrees or 2π radians.

What causes phase delay in a circuit?

Phase delay is caused by the reactive components in a circuit, which create a phase shift between the input and output signals. This is due to the fact that these components store and release energy at different rates, causing a time delay in the output signal.

How does phase delay affect circuit performance?

Phase delay can affect circuit performance in several ways. It can cause distortion in the output signal, making it different from the input signal. It can also affect the frequency response of the circuit, leading to changes in the amplitude and phase of the output signal.

How can phase delay be minimized in a circuit?

Phase delay can be minimized by using components with lower reactance values, such as capacitors with higher capacitance and inductors with lower inductance. It can also be reduced by using active components, such as op-amps, which have a high input impedance and can compensate for the phase delay caused by reactive components.

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