Design and Fabrication of a 175 MHz Low-pass Filter
1. Design and Simulation of Different Approaches
First, I performed the ideal simulation on ADS
Figure 1: Simulation on ADS
The next step was to simulate on CST Suite software, which required drawing inductors
for the simulation.
At this stage, the circuit moved closer to practical implementation. The inductor
simulation demanded in-depth technical knowledge and, more importantly, the ability to
use the software to draw accurately. Although thoroughly researched, this approach was
not feasible and eventually returned to the ideal LC
Figure 2: Simulation method of coil inductor on CST
Figure 3: Simulation results of the coil inductor approach
2. Circuit Completion
At this stage, the process returned to the initial approach using ideal LC component
simulation.
Besides theoretical calculations, it was necessary to consider practical aspects such as
component availability, dimensions, manufacturability, and cost.
Initially, the circuit was designed on Rogers substrate, but to reduce costs, the student
changed to PTFE material, even though the circuit had already been completed with the
original substrate.
During the final simulation stage, the student faced many difficulties in optimizing the
dimensions and finding available components on the market with the smallest tolerances
while still ensuring performance and cost requirements.
After solving these problems, the student collaborated with the mechanical team to
finalize the circuit design, adjusting the shape of the circuit to fit the project. Finally, the
circuit was fabricated for testing.
Figure 4. Completed Layout Circuit
Figure 5. Simulation results of the layout circuit
Figure 6. Fabricated circuit
Figure 7. Measurement results