This document outlines the design of 3kHz high-pass filters, including both first-order and second-order active filters. It discusses the principles of filtering, provides formulas and calculations for the filter designs, and highlights their respective performance characteristics. The first-order filter is simple and cost-effective, while the second-order filter offers enhanced performance with a steeper roll-off for better rejection of low-frequency signals.

1. MINI PROJECT
ELECTRONIC DESIGN WORKSHOP
PRESENTED BY :-
Topic : Design of 3khz High Pass Filter
Amit Kumar (ECE/2021/10)
Anuragsinh Singh(ECE/2021/18)
Abhradeep Kanrar(ECE/2021/20)
Sk. Asfakur Rahaman (ECE/2021/23)
Romit Raj Singh (ECE/2021/24)
Sagnik Sanyal(ECE/2021/26)

2. CONTENT
01
02
03
04
WHAT IS A FILTER?
DESIGN OF FIRST ORDER ACTIVE HIGH PASS FILTER WITH
CUT-OFF FREQUENCY 3KHZ
DESIGN OF SECOND ORDER ACTIVE HIGH PASS FILTER WITH
CUT-OFF FREQUENCY 3KHZ
DISCUSSIONS

3. WHAT IS A FILTER?
A filter is a circuit capable of passing (or amplifying) certain frequencies while
attenuating other frequencies. Thus, a filter can extract important frequencies from
signals that also contain undesirable or irrelevant frequencies.
Different types of
filters are:

4. Formulas :
DESIGN OF FIRST ORDER ACTIVE HIGH PASS FILTER WITH
CUT-OFF FREQUENCY 3KHZ
A first-order (single-pole) Active High Pass Filter as its name implies, attenuates low frequencies and
passes high frequency signals. It consists simply of a passive filter section followed by a non-
inverting operational amplifier. The frequency response of the circuit is the same as that of the
passive filter, except that the amplitude of the signal is increased by the gain of the amplifier and for
a non-inverting amplifier the value of the pass band voltage gain is given as 1 + R2/R1, the same as
for the low pass filter circuit.
First Order Active High Pass Filter with Amplification
Cut Off Frequency ,
Gain of opamp,

5. CALCULATIONS
Here , Cutoff Frequency = 3KHz
taking Capactiance value , C = 0.01uF and R1 = R2 = 1 kohm
Since we know cut off frequency ,
Therefore ,
So R = 5.305 kohm
Now , = 1+(1/1) = 2
So, Gain in dB = 20log Af = 20log2 = 6.02dB

6. Without Amplification
FIRST ORDER ACTIVE HIGH PASS FILTER WITH CUT-OFF
FREQUENCY 3KHZ

7. Output

8. With Amplification
FIRST ORDER ACTIVE HIGH PASS FILTER WITH CUT-OFF
FREQUENCY 3KHZ

9. Output

10. Formulas :
DESIGN OF SECOND ORDER ACTIVE HIGH PASS FILTER WITH
CUT-OFF FREQUENCY 3KHZ
As with the passive filter, a first-order high pass active filter can be converted into a second-order
high pass filter simply by using an additional RC network in the input path. The frequency response of
the second-order high pass filter is identical to that of the first-order type except that the stop band
roll-off will be twice the first-order filters at 40dB/decade (12dB/octave). Therefore, the design steps
required of the second-order active high pass filter are the same.
Second Order Active High Pass Filter
Cut Off Frequency ,
Gain of op-amp, Af = 1 + (R2/R1)
Damping factor: g =(𝟑−𝑨𝒇)/𝟐

11. CALCULATIONS
Here the cut off frequency = 3KHz
Let, R3=R4=R and C1=C2=C and We are taking the capacitance value C = 0.01uF
So, Cut off frequency , So, R = 1/(2∗𝑝𝑖∗3000∗0.01∗10^−6) = 5.305
Kohm
For Second order low-pass filter , g = 0.707
So, Damping factor: g=0.707=(3-Af)/2 ; So, Af=1.586
So, Gain in dB = 20log Af = 4dB
We know, Af = 1.586= 1+R2/R1 ; So,R2=R1*0.586
So, We are considering R2 = 1 kOhm and R1 = 586Ohm

12. Without Amplification
SECIOND ORDER ACTIVE HIGH PASS FILTER WITH CUT-OFF
FREQUENCY 3KHZ

13. Output

14. DISCUSSIONS
The first-order active high pass filter provides a simple yet effective solution for
filtering out low-frequency signals while allowing high-frequency signals to pass
through. With its straightforward design consisting of just one capacitor and one
resistor, it offers ease of implementation and low cost. However, its roll-off rate
of 20 dB/decade limits its effectiveness in applications requiring steep cutoff
slopes. Nonetheless, for many audio and basic signal conditioning applications,
the first-order active high pass filter proves to be a versatile and reliable choice.
In contrast, the second-order active high pass filter offers a more advanced
solution with a steeper roll-off rate of 40 dB/decade, making it suitable for
applications demanding greater attenuation of low-frequency signals. By
incorporating additional reactive components, such as capacitors and inductors,
this filter achieves enhanced performance in terms of frequency response and
filtering characteristics. Despite being more complex to design and implement
compared to the first-order counterpart, the second-order active high pass filter
is preferred in applications where tighter control over frequency response and
better rejection of unwanted signals are crucial.

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