[SOLVED] How to find the order of a circuit?

How to find out the order of a complex circuit

What's the easiest method to find out the order of a complex circuit consisting of inductors, caps and resistors? I know that there are many methods but I want the easiest one.

I think differential equation method is easy. And there are chances of getting wrong answers in other methods.

The Laplace Transform pf an inductor is s*(Inductance value) and the Laplace transform of a capacitor is s^*-1*(Capacitance Value).As far as possible,you can identify series and parallel connections of inductors or capacitors by looking at them and they can be simplified to get equivalent values.(Note:This can be used if they are in series with a resistor,the order of the circuit will not change).The presence of a s and a s^-1 term gives me a second order equation(appears if current doesn't split).Analyze each node and you can easily determine the order of the loop.See the order from the source towards the node and add the order each time you come across a node ,add the order that you have identified with each node and the result will give the order of the circuit.

Re: How to find out the order of a complex circuit

iVenky said:

What's the easiest method to find out the order of a complex circuit consisting of inductors, caps and resistors? I know that there are many methods but I want the easiest one.

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If you have the transfer function in a so called "normal" form (with polynominals for the complex frequency s in the numerator as well as the denominator) the order of the system is given by the highest degree of s in the denominator (example: s^3 gives third order).

Just count the number of reactive components. Let us call it A. Then count the number of capacitive loops and inductive cut sets in the circuit B and C respectively. Then the order of circuit is A-B-C. Very easy. For convenience, i have attached an example.

Hello. I have heard of another method where they use no of independent voltages across the capacitor or independent current source through an inductor. i can't remember the exact way. Can anyone help me with this?

Thanks

That is basically what i have said in my previous comment!