22-02-2013, 11:59 AM
To design HPF (Multistage) using OPAMP
HPF (Multistage).docx (Size: 34.56 KB / Downloads: 20)
OBJECTIVE: - To design HPF (Multistage) using OPAMP.
(I) PRACTICAL SIGNIFICANCE: -It is used to obtain stop band response of the filter approaching ideal stop band characteristics.
(II) COMPETENCY/SKILL: - Design and testing.
(III) EXPERIMENT OBJECTIVE: -
1. To design HPF (Multistage) using OPAMP.
2. Calculate to cut-off frequency
3. Calculate to quality factor
(IV) THEORETICAL BACKGROUND: -
Higher order filters, such as third, fourth, fifth, and so on, are built simply by using the first and second order filters. The simplest way to build a higher order high pass filter is by cascading a first or second order filter with a second order.
The overall filter gain is equal to the product of the individual voltage gains of the filter sections. Hence, Av = Av1 × Av2
The cut off frequency is given as fL = 1/ 2πRC
For second order high pass filter the voltage gain is
Vo/ Vin = AF/ √ [1 + (fL / f) 4]
Where AF = 1 + RF / R1
Where AF = 1 = pass band gain of the filter.
f = frequency of the input signal (Hz)
fL = low cutoff frequency (Hz)
The high pass filter has a constant gain AF from fL frequency (DC to lower cut off frequency fL). At fL the gain is 0.707 AF & before fL it decreases at a constant rate (-40 db / decade) with an increase in frequency.
PROCEDURE: -
1. Now connect the circuit as per diagram.
2. Apply an input frequency in different steps from a function generator by keeping its input voltage constant.
3. Output voltage note down and calculate voltage gain.
4. Compare practical & theoretical voltage gain.