AReS

PART9Active Filter Circuit

Experiment 2 :High-Pass Filter

Theory

fig9-6

Fig. 9-6Equivalent Butter Worth High Pass Filter

As in fig. 9-6, VCVS high pass filter is the circuit in which the location of resistance and condenser is changed in equivalent VCVS low pass filter, and its pass band gain or the cutoff frequency is same as that of low pass filter.

f_c=1/2πRC

The pass band gain is 1.586, that is, +4dB.

Experiment Process

fig9-7

Fig. 9-7HPF Circuit(a)

fig9-8

Fig. 9-8HPF Circuit(b)

1. In Circuit-2 of M-09, make the both ends of 2c-2d, 2f-2g shorted and compose a circuit as in fig. 9-7.

2. Apply the input of 1V(rms) to the both ends of 2a-2b. Change the frequency as given in table 9-2 and measure the output voltage and record it in the relevant column.

3. This time, make the 2c-2e, 2f-2h terminals shorted and compose a circuit as in fig. 9-8.

4. Apply the input of 1V(rms) and use the frequency given in table 9-2 to measure the output voltage and record it.

5. Draw a graph in the experiment result report using the measured value.

tab1

Experiment 9-2.1 High Pass Filter experiment (In Circuit-2 of M09, compose circuits as in fig. 9-7 and fig. 9-8.)

1.Connection(Circuit-1 of M09), Fig. 9-7 HPF Circuit(a)

1.Circuit Connection

Resistance R1, R3 Connection; Connect between 2c terminal and 2d terminal, between 2f terminal and 2g terminal of Circuit-2 with yellow lines.

2.Power Connection

It is connected internally.

3.Measuring Instrument Connection

Function Generator Connection

Plug in BNC cable to BNC terminal of Signal Output on front panel and connect red line to 2a terminal of Circuit-2, and black line to 2b terminal.

Voltmeter Connection

Input Voltage Measurement Connection: - Connect between 2a terminal of Circuit-2 and A+ terminal of Signal Input CH A on the front panel of Multimeter with red line, and between 2b terminal and A- terminal with black line.

Output Voltage Measurement Connection: Connect between 2i terminal of Circuit-2 and B+ terminal of Signal Input CH B on the front panel of Multimeter with red line, and between 2j terminal and B- terminal with black line.

2.Wiring Diagram

flash

3.Measurement

1Choose analog output at Touch LCD panel, click Function Generator and set up Amplitude Range as 20vpp, and click arrow bottom of Amplitude and set up as amplitude 15%.
Set up Signal as sine , and choose 100 at Frequency and click arrow to set up as frequency 200.
Click on and apply the output of Function Generator to input of Circuit-2.

Changing 1V(rms) as Vpp can be done by the formula below.
V_PP=V_rms×2√2=1V×2×1.414=2.83V_PP
The 15% of 20Vpp set up above is 3.0Vpp so it is set up as the approximation of 1V(rms).
2Measurement
Choose analog input at front panel, choose Volt & Ampere Meter tab and click voltage, ac, rms at CH A, CH B and record the output voltage measured at CH B in the relevant column of table 9-2.

Choose quick launch on the left bottom of the screen, click Analog Output and click arrow right of Frequency at Function to change the frequency as in table 9-2. Record the measured output voltage in the relevant column of table 9-2.

After the measurement, click on red at quick launch screen and cut off the output.
3Fig. 9-8 HPF Circuit(b) Experiment
Resistance R2, R4 Connection: Change the connection between R1 and R3 to between 2c terminal and 2e terminal, and between 2f terminal and 2h terminal of Circuit-2 and connect with yellow lines.

Wiring Diagram

flash

Execute as the process 2) above and record the result in the relevant column of table 9-2.

After the measurement, click on red at quick launch screen and cut off the output.

4.Calculation

1. Calculate the cutoff frequency when connecting resistance R1 and R3, and .when connecting resistance R2 and R4.

f_c=1/(2π√R1R2C1C2)

If making R1 and R2 same, and C1 and C2 same, the cutoff frequency is as below.

f_c=1/2πRC

Experiment Result Report

result
Title	High-Pass Filter	Date
Department		Id Number		Name

1. Experiment Result Table

2. Review and Explanation

1) Using the measured result in table 9-2, draw the characteristic curve in the graph.

section paper Characteristic of Active Filter(HPF)

2) Using the figure and formula below, calculate the amplification degree Av, Q, cutoff frequency and 3dB frequency of circuit 9-7, 9-8. (When Q=0.699, Kc =1, K₃=1)

A_v=R_A/R_B +1,Q=1/(3-A_v ),f_p=1/2πRC,f_0=K_0 f_P,f_c=K_C f_P,f_3dB=K_3 f_P

fig02

Input Frequency [㎐]		200	400	600	800	1k	1.2k	1.4k	1.6k	1.8k	2k	3k
Output	Fig. 9-7
Output	Fig. 9-8

	Amplification Degree A_v	Q	Polar Frequency f_P	Resonance Frequency f₀	Cutoff Frequency f_C	3dB Frequeycn f_3dB
Circuit 9-7
Circuit 9-8

PART9Active Filter Circuit

Experiment 2 :High-Pass Filter

Theory

Experiment Process

Experiment 9-2.1 High Pass Filter experiment (In Circuit-2 of M09, compose circuits as in fig. 9-7 and fig. 9-8.)

1.Connection(Circuit-1 of M09), Fig. 9-7 HPF Circuit(a)

1.Circuit Connection

2.Power Connection

3.Measuring Instrument Connection

2.Wiring Diagram

flash

3.Measurement

flash

4.Calculation

Experiment Result Report

1. Experiment Result Table

2. Review and Explanation

1) Using the measured result in table 9-2, draw the characteristic curve in the graph.

2) Using the figure and formula below, calculate the amplification degree Av, Q, cutoff frequency and 3dB frequency of circuit 9-7, 9-8. (When Q=0.699, Kc =1, K3=1)

3. Discuss the experiment result.

2) Using the figure and formula below, calculate the amplification degree Av, Q, cutoff frequency and 3dB frequency of circuit 9-7, 9-8. (When Q=0.699, Kc =1, K₃=1)