Troubleshooting Analog Delay Line Simulation in Multisim

In summary, the multisim simulation is not reflecting the input. The Zo of the TL needs to be greater than the edge rate of the signal in order to reflect the input. The parallel resistances in the TL are not providing enough conductance to reflect the input.
  • #1
Hiranya Pasan
30
3
I'm trying to construct an analog delay (series of low pass filters) and demonstrate the properties of a transmission line (reflection, attenuating etc.) using a multisim simulation (my attempt attached below). But on the oscilloscope I don't get any kind of reflection. What should I do?
1zlzlgh.jpg

Thank you
 
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  • #2
Can you show us the waveforms you are getting? Also, I don't think C1 will do much of anything useful if you are driving the input to the TL with an idea voltage source. What is the output resistance that you have assigned to V1? Is V1 a sine wave source or a pulse source?
 
  • #3
This is the wave form I get for sine and square pulse inputs
347i4v9.jpg
2v0ew7p.jpg

I get the the delay output but no reflection effects. First I tried to get the waveform for an open circuit.
 
  • #4
What is the target Zo for your TL? It sure looks very lossy -- are those 1000 Ohm resistors in the TL?
 
  • #5
berkeman said:
What is the target Zo for your TL? It sure looks very lossy -- are those 1000 Ohm resistors in the TL?

No such target, but I only need to demonstrate delay and reflection effects. No need to use specific values.
 
  • #6
Hiranya Pasan said:
No such target, but I only need to demonstrate delay and reflection effects. No need to use specific values.
Well, you need the Zo to calculate the expected reflections of any mismatched termination, no?

Also, why is it so lossy? The parallel resistances are meant to represent the conductance of the dielectric insulator in the TL (at the test frequency). 1000 Ohms is way too much conductance, IMO.
 
  • #7
I don't think the circuit as drawn will work because it's not a transmission line. The main issue is each filter bank is referenced to the same potential. To make this work you'll need inductance in the return between each too. Also, to make the lumped model approximation correct the time constant of each stage has to be >> than the edge rate of the signal (which is not the same as it's frequency). (Note: because "ground" is not the same on both sides of the filter you'll need to find the delay through the two port network. This is not the same as the equations you typically use for a garden variety LC filter.) This is definitely the hard way to do it but if you can make it work, and know why it is working, then you'll definitely have a much better understanding of transmission lines.
 
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1. What is an Analog Delay Line in Multisim?

An Analog Delay Line in Multisim is a circuit component that allows you to introduce a time delay in an analog signal. It is commonly used in electronic systems to synchronize signals or to create echo or reverberation effects.

2. How does an Analog Delay Line work in Multisim?

An Analog Delay Line in Multisim works by using a series of capacitors and resistors to create a delay in the signal. The signal is first converted to a series of digital values, then fed through the capacitors and resistors to create the desired delay, and finally converted back to an analog signal.

3. What are the advantages of using an Analog Delay Line in Multisim?

An Analog Delay Line in Multisim allows for precise control over the amount of delay in a signal. It is also a cost-effective solution for introducing delays in analog signals compared to using physical components. Additionally, it can be easily adjusted and modified in Multisim to test different delay values.

4. Are there any limitations to using an Analog Delay Line in Multisim?

One limitation of using an Analog Delay Line in Multisim is that it can introduce noise or distortion in the signal, especially if the delay is too long. It is important to carefully design and test the circuit to minimize these effects. Additionally, the maximum delay time may be limited by the capacitance and resistance values used in the circuit.

5. Can an Analog Delay Line be used in combination with other Multisim components?

Yes, an Analog Delay Line can be used in combination with other Multisim components to create more complex circuits. For example, it can be combined with filters, amplifiers, or other delay lines to achieve different signal processing effects. Multisim allows for easy integration and simulation of these components together.

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