Day Twenty-Five and Day Twenty-Six - Passive RL Filter

On day twenty-five, we talked about transfer function and how they are used in for frequency response. Also, we talked about series and parallel resonance.

Given a transfer function above, we are able to approximate the curve of the H vs frequency and angle vs frequency.

That is how the curves look like.
Graphing Technique: We first draw the curve of each part, then we add up each part at one point to represent the final value of that point.

Resonance is a condition in an RLC circuit in which the capacitive and inductive reactances are equal in magnitude, which implies a purely resistive impedance.


On Day Twenty-Six, we talked about filters, YOHO.!!!
Filters is a very important component in electronic because it enables us to perform many things such as discriminating signal. There are four basic types of filters - high pass filter, low pass filter, band pass filter, and band stop filter.
The designated function of these filters is to pass a particular range of frequency signal and attenuate other frequency.
Low pass filter will pass low frequency(C in RC Series or R in RL Series), high pass filter (R in RC series)will pass high frequency, band pass filter (R in RLC Series)will pass middle frequency, and band stop filter (LC in RLC Series)will pass frequency other than the middle frequency.

Pre-Lab:

From the given circuit above, we calculated the cutoff angular frequency of the schematic will be at 1*10^5 radi/s = 15915Hz.

Result:
Before cutoff frequency (Resistor Voltage)

As we can observe from above graphs, the frequency before the cutoff frequency will have approximately the gain of one and a bit of phase shift.

At the cutoff frequency and after:

After cutoff frequency, we can observe that the gain start decreasing and there are phase shifts. This results from the imaginary part of the equation (the omega is not zero anymore).

Before the cutoff voltage (inductor voltage)

We can observe that before the cutoff voltage, there are phase shifts, and the gain is less than one.

In and after the cutoff frequency:

We can observe that as the frequency approaches infinity, the gain of the voltage approaches close to one.

Data:

Here is the data we measured and calculated.

Comparison:

Above are the graphs for phase vs frequency and transfer function vs frequency of the voltage output of the resistor.

Above are the graphs for phase vs frequency and transfer function vs frequency of the voltage output of the inductor.

Summary:

From the data graph above, we can conclude that the resistor voltage acts like a low-pass filter while the inductor voltage acts like a high-pass filter. However, from our data graph, we can see that the experimental gain of the voltage has a big difference with our theoretical gain, but the trend of the gain is almost the same; therefore. we can still conclude that in passive RL circuit, R acts like low-pass filter while L acts like high-pass filter.