# Understanding the Gain and Bode Plot of a Low Pass Filter Circuit with C1 > C2

• Engineering
• Fat Dapper Cat
In summary, the conversation discussed the gain and bode plot for a circuit with two capacitors and a resistor, where the question was to identify the type of filter when C1 is much greater than C2. The expert provided a summary of the steps to analyze the circuit, including how to find the corner frequency and why the second capacitor can be ignored in certain cases. The conversation also addressed a potential mistake made by one of the participants, which was later corrected.
Fat Dapper Cat
Thread moved from Electrical Engineering forum, so no template included.

The question wants to know the gain of the this circuit, as well as a bode plot for the frequency response, and what type of filter this is when C1 is much greater than C2. Could someone double check my answers and assist in the bode plot?

My attempt:

For the Gain:

If C1 is much greater than C2 I said the filter would be a low pass filter.

I'm not sure how to proceed with the Bode Plot.

The simplest way to analyze the circuit is to note that ## C_1## and ##C_2 ## form a capacitive voltage divider connected to ## V_{IN} ##. The divider is equivalent of ## C_1## and ##C_2 ## in parallel connected to the voltage source ## V_{eq} = V_{IN} \frac {C_1} {C_1 + C_2} ##. Then connect the resistor between the output of the two capacitors and the ground. What you have is a high pass filter with the corner frequency given by ## \omega _c = R *(C_1+C_2)##
If ##C_1 \gg C_2 ##, then you can simply ignore the second capacitor. The equivalent circuits is showing you why you can do that.
I'm attaching a drawing of the equivalent circuit.

Won't there be a pole due to R1C2?

Fat Dapper Cat said:
My attempt:

Oops! You're right. No pole there. I just worked it out.

## 1. What is the purpose of a gain of filter circuit?

A gain of filter circuit is used to amplify or attenuate specific frequencies of an electrical signal. This allows for better control and manipulation of the signal for various purposes.

## 2. How does a gain of filter circuit work?

A gain of filter circuit uses components such as resistors, capacitors, and inductors to create a specific frequency response. The signal is fed through the circuit, and depending on the values of the components, certain frequencies will be amplified or attenuated.

## 3. What are the different types of gain of filter circuits?

There are several types of gain of filter circuits, including low-pass, high-pass, band-pass, and band-stop filters. These filters have different frequency response characteristics and are used for different purposes.

## 4. Can a gain of filter circuit affect the overall signal amplitude?

Yes, a gain of filter circuit can affect the overall signal amplitude. Depending on the design and values of the components, the signal can be amplified or attenuated. However, the goal of the circuit is to maintain a constant gain for the desired frequencies.

## 5. What are some common applications of gain of filter circuits?

Gain of filter circuits are used in a variety of applications, including audio amplifiers, radio frequency communication, signal processing, and instrumentation. They are also commonly used in electronic devices to filter out unwanted noise and interference.

• Engineering and Comp Sci Homework Help
Replies
9
Views
2K
• Engineering and Comp Sci Homework Help
Replies
3
Views
1K
• Engineering and Comp Sci Homework Help
Replies
9
Views
3K
• Engineering and Comp Sci Homework Help
Replies
16
Views
1K
• Engineering and Comp Sci Homework Help
Replies
10
Views
2K
• Engineering and Comp Sci Homework Help
Replies
6
Views
2K
• Engineering and Comp Sci Homework Help
Replies
8
Views
3K
• Engineering and Comp Sci Homework Help
Replies
4
Views
1K
• Engineering and Comp Sci Homework Help
Replies
4
Views
3K
• Engineering and Comp Sci Homework Help
Replies
4
Views
2K