Active High Pass filter

Aim:- Study of the Active High Pass Filter and to Evaluate:

  •     low cutoff frequency of Low pass filter.
  •     Pass band gain of High Pass Filter. 
  •     Plot the frequency response of high Pass Filter.

Apparatus :-

Analog board of AB51 ,DC power supplies +12V, −12V from external source or ST2612 Analog Lab, Function generator or ST 2612 Analog Lab., Oscilloscope, Multi meter, 2 mm patch cords.

Theory

An electric filter is a frequency selective circuit that passes electric signals of specific band of frequencies and attenuates signal of frequencies outside this band. Depending on the type of elements used in their construction filters may be classified as passive or active filters. Elements used in passive filters are resistors, capacitors and inductors.
 Active filter consists of active components such as Op-amp, transistors with passive elements.
High Pass Filter: It is a frequency selective circuit, which passes signals of frequencies above its low cut off frequency ($f_L$) and attenuates signals of frequencies below $f_L$\\

Procedure:-

- Connect Ohmmeter between Vin and Test point 3. Adjust resistance value to 15.9K by varying the potentiometer 22K of High pass filter to set the Low cutoff frequency $(f_L)$ at 1K.
- Connect $+$12V and $−$12V DC power supplies at their indicated position from external source or ST2612 Analog Lab. 
- Switch ‘On’ the power supply.
- Connect a sinusoidal signal of amplitude 1V (p-p) of frequency 100 Hz to the Test point $V_{in}$ of high pass filter from external source or ST2612 Analog Lab.
- Observe output on oscilloscope by connecting Test point $V_out$ to oscilloscope
- Increase the frequency of input signal step by step and observe the effect on output $V_{out}$ on oscilloscope.
- Tabulate different values of $V_{out}$, gain, gain (dB) at different values of input frequency.
- Plot the frequency response of high pass filter using the data obtained at different input frequencies.
- Perform the same procedure at different Cutoff frequencies.









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