The filter circuit of "analog circuit design"

1. The type of filter circuit and the advantages and disadvantages of each type.
2. Filter circuit design (take Butterworth type low pass for example).

3. According to the principle of low-pass filter circuit to promote the design of high-pass, band-pass, band resistance.

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1. The type of filter circuit and the advantages and disadvantages of each type.

1.1 Butterworth Type (Butterworth)

Advantage: The frequency response curve in the passband is maximized flat and without fluctuation.

Disadvantage: Band attenuation is slow.

1.2 Chebyshev type (Chebyshev)

Advantage: The frequency response curve in the passband is not as smooth as Butterworth.

Disadvantage: The band attenuation is faster.

1.3 Beta type (Bessel)

Advantage: Linear filter with maximum flat group delay (linear phase response), commonly used in audio overpass systems.

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2. Filter circuit design (take Butterworth type low pass for example)

The design of the filter circuit involves two parameters: cutoff frequency, order

Example: design of a Butterworth low-pass filter up to 75Hz, to 150Hz attenuation to 30dB

Step One: Determine the order, according to

According to the formula: A = W1 (maximum attenuation frequency)/w2 (up to frequency)

a = 150hz/75hz = 2;

When a = 2, the attenuation multiplier is 30dB, according to the order number is 5 order.

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Step Two: Determine the circuit structure of the order number

second-order section three-stage section

The order calculated according to step number: 5 = 2 + 3; (if 4 is 2 + 2).

The 5-order is equal to the second-order section and the third section of the splicing.

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Step Three: Determine the parameters

Solution Normalization: ① First determine r = Z = 50K; (Low resistance to large points, frequency resistance small point)

② according to the formula: FSF = 2π*f (f for up to frequency)

FSF = 2π* 75 = 471

③ determining capacitance: According to the data in the table

c1= 1.7530/(fsf*z) = A. NF

c2= 1.3540/(fsf*z) = NF

c3= 0.4214/(fsf*z) = NF

c4= 3.2350/(fsf*z) = 137 NF

c5= 0.3090/(fsf*z) = NF

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The final result, such as:

Multisim Simulation Results:

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The filter circuit of "analog circuit design"