RLC i dont understand

BobaMosfet

Joined Jul 1, 2009
2,110
In this case, you have one signal input @ 100MHz, for 3 different filter circuits. In any AC circuit if you find a capacitor, it's purpose is to limit current flow. It does this through reactance. With a slow frequency, the capacitor has time to discharge more fully, so more signal gets through. If you raise the frequency, the capacitor has less time to discharge, so begins to block the signal. The smaller the capacitor is, the more quickly it is filled. The size of the capacitor and the speed at which it is allowed to discharge is what filters the signal.

The majority of filtering is being done by the first 2 components (R5 & C6, R1 & L6, and R3 & C4). The resistor determines the rate of charge/discharge and the capacitor or inductor uses it's field to control voltage/current.

Each of these 3 filters utilizes a tank circuit (C5 & L5, C1 & L1, and C3 & L3), next which stores and returns energy to the circuit increasing the voltage level (signal strength).

The 2 following component in each section is a second filter to ensure proper rejection.

The values you are asking about were simply chosen arbitrarily by the author of the text in order to demonstrate wave shapes in the tutorial. You should consider getting a simulator, and implementing the circuit and walking through the tutorial that way so you can make changes on the fly and see what the circuit does, to match the tutorial.
 

Thread Starter

michael1978

Joined Jun 29, 2014
309
In this case, you have one signal input @ 100MHz, for 3 different filter circuits. In any AC circuit if you find a capacitor, it's purpose is to limit current flow. It does this through reactance. With a slow frequency, the capacitor has time to discharge more fully, so more signal gets through. If you raise the frequency, the capacitor has less time to discharge, so begins to block the signal. The smaller the capacitor is, the more quickly it is filled. The size of the capacitor and the speed at which it is allowed to discharge is what filters the signal.

The majority of filtering is being done by the first 2 components (R5 & C6, R1 & L6, and R3 & C4). The resistor determines the rate of charge/discharge and the capacitor or inductor uses it's field to control voltage/current.

Each of these 3 filters utilizes a tank circuit (C5 & L5, C1 & L1, and C3 & L3), next which stores and returns energy to the circuit increasing the voltage level (signal strength).

The 2 following component in each section is a second filter to ensure proper rejection.

The values you are asking about were simply chosen arbitrarily by the author of the text in order to demonstrate wave shapes in the tutorial. You should consider getting a simulator, and implementing the circuit and walking through the tutorial that way so you can make changes on the fly and see what the circuit does, to match the tutorial.
thank you
 

MrAl

Joined Jun 17, 2014
11,396
Hello to everbody can you help me how come C6 to be 10p and c5 13.5 and and l1 to be 190n and L6 240n
i start with 100Meghz, with one circuits 50/XL or 50/XC now become three different thanks
i take it from this tutorial

View attachment 145319
Hi,

I am quoting your first post again so we can see the three circuits again and note that the topology is the same for each of the three when we see that there are two resistors and four reactive elements which we can call impedances Z1, Z2, Z3, and Z4 in order from left to right, and we also notice that both resistors are the same value so we can call them BOTH R5 for convenience. We can also call the nodes v1, v2, v3 in order from right to left, or v3, v2, v1 in order from left to right (input node is not counted). We then can write the general topological solutions for ALL THREE CIRCUITS with just one set of equations:

v1=(E1*R5*Z2*Z3)
/(Z2*Z3*Z4+Z1*Z3*Z4+R5*Z3*Z4+Z1*Z2*Z4+R5*Z2*Z4+Z1*Z2*Z3+2*R5*Z2*Z3+R5*Z1*Z3+R5^2*Z3+R5*Z1*Z2+R5^2*Z2)

v2=(E1*Z2*Z3*(Z4+R5))
/(Z2*Z3*Z4+Z1*Z3*Z4+R5*Z3*Z4+Z1*Z2*Z4+R5*Z2*Z4+Z1*Z2*Z3+2*R5*Z2*Z3+R5*Z1*Z3+R5^2*Z3+R5*Z1*Z2+R5^2*Z2)

v3=(E1*(Z2*Z3*Z4+Z1*Z3*Z4+Z1*Z2*Z4+Z1*Z2*Z3+R5*Z2*Z3+R5*Z1*Z3+R5*Z1*Z2))
/(Z2*Z3*Z4+Z1*Z3*Z4+R5*Z3*Z4+Z1*Z2*Z4+R5*Z2*Z4+Z1*Z2*Z3+2*R5*Z2*Z3+R5*Z1*Z3+R5^2*Z3+R5*Z1*Z2+R5^2*Z2)

To evaluate for a given circuit, replace the impedances Z1, Z2, Z3, Z4, with the respective impedances for the particular circuit.
Because all three nodes are solved, you can solve for input Z, output Z, and peak resonant frequency, and Q if you like, or just plot the output like they did in the pdf file.

For example the input impedance looking INTO the element right AFTER R5 is:
Zin=(Z2*Z3*Z4+Z1*Z3*Z4+Z1*Z2*Z4+Z1*Z2*Z3+R5*Z2*Z3+R5*Z1*Z3+R5*Z1*Z2)/(Z3*Z4+Z2*Z4+Z2*Z3+R5*Z3+R5*Z2)
 
Last edited:

Thread Starter

michael1978

Joined Jun 29, 2014
309
In this case, you have one signal input @ 100MHz, for 3 different filter circuits. In any AC circuit if you find a capacitor, it's purpose is to limit current flow. It does this through reactance. With a slow frequency, the capacitor has time to discharge more fully, so more signal gets through. If you raise the frequency, the capacitor has less time to discharge, so begins to block the signal. The smaller the capacitor is, the more quickly it is filled. The size of the capacitor and the speed at which it is allowed to discharge is what filters the signal.

The majority of filtering is being done by the first 2 components (R5 & C6, R1 & L6, and R3 & C4). The resistor determines the rate of charge/discharge and the capacitor or inductor uses it's field to control voltage/current.

Each of these 3 filters utilizes a tank circuit (C5 & L5, C1 & L1, and C3 & L3), next which stores and returns energy to the circuit increasing the voltage level (signal strength).

The 2 following component in each section is a second filter to ensure proper rejection.

The values you are asking about were simply chosen arbitrarily by the author of the text in order to demonstrate wave shapes in the tutorial. You should consider getting a simulator, and implementing the circuit and walking through the tutorial that way so you can make changes on the fly and see what the circuit does, to match the tutorial.
thnx of lot one more time............
 

Thread Starter

michael1978

Joined Jun 29, 2014
309
Hi,

I am quoting your first post again so we can see the three circuits again and note that the topology is the same for each of the three when we see that there are two resistors and four reactive elements which we can call impedances Z1, Z2, Z3, and Z4 in order from left to right, and we also notice that both resistors are the same value so we can call them BOTH R5 for convenience. We can also call the nodes v1, v2, v3 in order from right to left, or v3, v2, v1 in order from left to right (input node is not counted). We then can write the general topological solutions for ALL THREE CIRCUITS with just one set of equations:

v1=(E1*R5*Z2*Z3)
/(Z2*Z3*Z4+Z1*Z3*Z4+R5*Z3*Z4+Z1*Z2*Z4+R5*Z2*Z4+Z1*Z2*Z3+2*R5*Z2*Z3+R5*Z1*Z3+R5^2*Z3+R5*Z1*Z2+R5^2*Z2)

v2=(E1*Z2*Z3*(Z4+R5))
/(Z2*Z3*Z4+Z1*Z3*Z4+R5*Z3*Z4+Z1*Z2*Z4+R5*Z2*Z4+Z1*Z2*Z3+2*R5*Z2*Z3+R5*Z1*Z3+R5^2*Z3+R5*Z1*Z2+R5^2*Z2)

v3=(E1*(Z2*Z3*Z4+Z1*Z3*Z4+Z1*Z2*Z4+Z1*Z2*Z3+R5*Z2*Z3+R5*Z1*Z3+R5*Z1*Z2))
/(Z2*Z3*Z4+Z1*Z3*Z4+R5*Z3*Z4+Z1*Z2*Z4+R5*Z2*Z4+Z1*Z2*Z3+2*R5*Z2*Z3+R5*Z1*Z3+R5^2*Z3+R5*Z1*Z2+R5^2*Z2)

To evaluate for a given circuit, replace the impedances Z1, Z2, Z3, Z4, with the respective impedances for the particular circuit.
Because all three nodes are solved, you can solve for input Z, output Z, and peak resonant frequency, and Q if you like, or just plot the output like they did in the pdf file.

For example the input impedance looking INTO the element right AFTER R5 is:
Zin=(Z2*Z3*Z4+Z1*Z3*Z4+Z1*Z2*Z4+Z1*Z2*Z3+R5*Z2*Z3+R5*Z1*Z3+R5*Z1*Z2)/(Z3*Z4+Z2*Z4+Z2*Z3+R5*Z3+R5*Z2)
thanks a lot ;-)
 
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