Bode plot for first order high pass (RL) - reality vs theory

In summary, the conversation discusses a circuit with specific values for resistance and inductance, and the discrepancy between theoretical and measured values at lower frequencies. The cause of this difference is questioned, with suggestions such as the internal resistance or capacitance of the inductor. Additional information is requested, including the Zout of the generator, the ESR of the inductor, and the ESL of the resistor. It is suggested that adding these values into the simulation may result in a closer match to the measured results.
  • #1
Rectifier
Gold Member
313
4
Hey there!
So I have this circuit:
9sPBmWm.jpg

with R= 1kOhm and L=10mH
and for some reason the theoretical and real values differ drasticly for lower frequencies
J8Fycm0.jpg

Brown lines are representing the asymptotic and approximation lines.
Blue lines are connecting my measured values.
Amplitude is the amplitude of the transfer function in dB.

What can this shift in both amplitude and phase be caused by? Is it the internal resistance of the indoctor or is it the internal capacitance of the inductor or is it something else?
 
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  • #2
What is the Zout of the generator? What is the ESR of the inductor? What is the ESL of the resistor?

I think if you add these values into your simulation, you will get closer to your measured result... :smile:
 

1. What is a Bode plot for a first order high pass (RL) filter?

A Bode plot is a graphical representation of the frequency response of a system, in this case a first order high pass filter. It shows the gain and phase shift of the filter as a function of frequency. The RL in the name stands for the two components of the filter: a resistor (R) and an inductor (L).

2. How does the Bode plot for a first order high pass (RL) filter compare to theory?

The Bode plot for a first order high pass (RL) filter will closely match the theoretical response, with some slight deviations due to practical limitations and component tolerances. The shape and slope of the gain curve will be similar, and the phase shift will also follow the theoretical curve.

3. What is the significance of the cutoff frequency on a Bode plot for a first order high pass (RL) filter?

The cutoff frequency on a Bode plot for a first order high pass (RL) filter is the frequency at which the gain drops to -3dB (or 70.7% of the maximum gain). This frequency is important because it marks the point at which the filter begins to attenuate the input signal.

4. Can the Bode plot for a first order high pass (RL) filter be used to determine the filter's bandwidth?

Yes, the bandwidth of a filter can be determined by looking at the Bode plot. The bandwidth is the range of frequencies where the gain is within 3dB of the maximum gain. In a first order high pass (RL) filter, the bandwidth is equal to the cutoff frequency.

5. How does the Bode plot for a first order high pass (RL) filter change with different values of resistance and inductance?

The Bode plot for a first order high pass (RL) filter will change depending on the values of the resistor and inductor used. A larger resistor will result in a steeper slope and a higher cutoff frequency, while a larger inductor will result in a shallower slope and a lower cutoff frequency. Changing both the resistor and inductor values will also change the overall gain and phase shift of the filter.

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