Simulation Practices for Electronics and Microelectronics
Engineering
Dr. Graciano Dieck Assad / Ing. Matías Vázquez Piñón
Capstone Projects
EC-04. Transmission Line Lumped Parameter Model
Transmission lines can be modeled using a network containing R, L and C parameters, which are
discussed in your network analysis subjects. The transmission line model is very useful in predicting
propagation delay times, R-C interconnect losses and noise transmission in communication and
transmission networks. We will make a model of the transmission line using some given parameters.
We will also evaluate the propagation delays when we transmit a square waveform through the
circuit. The model is simplified by concentrating the R, L and C components in a common
transmission line block that describes a communication system that can be either current loop or
voltage transmission.
The purpose of this project is to design a transmission line lumped-parameter model with the
following specifications:
a. The source voltage waveform is a square waveform pulse that has 2.5 V amplitude, 2.5 V offset
(to generate a 0 to 5 V TTL digital waveform), 50% duty cycle, and a period of 10 ms.
b. Source voltage series resistor of 20 Ohms.
c. Load resistor of 1000 Ohms.
d. The parallel shunt capacitance can be set between 100 nF and 0.47 F at the source voltage and
at the load resistor.
e. The transmission block can be set as an L-R interconnect combo of any particular value, with
resistor ranging from 10 to 100 Ohms, and with the inductance ranging from 10 MHz to 200 MHz.
f. Use figure EC-04.1 as a reference to design your transmission line model.
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D . R . © I n s t i tu t o T e c no l ó g ic o y d e E s t u d i o s S u p er i o re s d e M o n te rr e y , M é x i c o 2 0 1 2
Simulation Practices for Electronics and Microelectronics
Engineering
Dr. Graciano Dieck Assad / Ing. Matías Vázquez Piñón
Figure EC-04.1. Transmission line lumped-parameter model
Report.
1. Provide the circuit schematic and analytical solution of the transmission line model.
2. Justify your considerations of parameters R, L or C using technical literature.
3. Time the domain simulation of the circuit when a square waveform feeds the circuit. Use a square
waveform having a 50% duty cycle and a 0 to 5 V, minimum and maximum values.
4. Show the simulated output pulse using the LTSpice cursors to show the peak value, transient
excursions, propagation delay estimation (from 50% of transmitted waveform to 50% of received
waveform), peak transient and other characteristics such as undershoots and settling times.
5. Describe how circuit parameters such as R, L or C modify the waveform transmission
characteristics.
6. Include references.
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