5.4.2.4
Example 4 

This example is adapted from T 1227/05.

Claim 1: 
A computer-implemented method for the numerical simulation of the performance of an electronic circuit subject to 1/f noise, wherein: 
(a)
the circuit is described by a model featuring input channels, noise input channels and output channels;
(b)
the performance of the input channels and the output channels is described by a system of stochastic differential equations;
(c)
an output vector is calculated for an input vector present on the input channels and for a noise vector y of 1/f-distributed random numbers present on the noise input channels; and
(d)
the noise vector y is generated by the following steps:
(d1)
setting the number n of random numbers to be generated;
(d2)
generating a vector x of length n of Gaussian-distributed random numbers;
(d3)
generating the vector y by multiplying the vector x with a matrix L defined according to equation E1*.

* It is assumed that equation E1 is explicitly specified in the claim.

Background: The claim is directed to a method carried out by a computer for the numerical simulation of the performance of an electronic circuit subject to 1/f noise, which is one of the main sources of noise in electronic circuits. Features (a)-(c) specify the mathematical model used in the numerical simulation. It involves a noise vector y of 1/f-distributed random numbers, i.e. random numbers having a particular statistical property typical of real (physical) 1/f noise. Steps (d1)-(d3) define the mathematical algorithm used for generating these random numbers. According to the description, this mathematical algorithm is particularly efficient in terms of computation time and storage resources required to generate the random numbers needed for the simulation.

Application of the steps of the problem-solution approach according to G‑VII, 5.4:

Step (i): The use of a computer to carry out the claimed method is a clearly technical feature. The question is whether the other features, in particular the mathematical algorithm of steps (d1)-(d3), also contribute to the technical character of the claimed subject-matter. Considered in isolation, steps (d1)-(d3) represent a mathematical method with no technical character. However, the claim is not directed to this mathematical method as such (which would be excluded from patentability under Art. 52(2)(a) and (3)) but is limited to a computer-implemented method in which this mathematical method serves the numerical simulation of the performance of an electronic circuit subject to 1/f noise, which is considered to be a technical purpose (G‑II, 3.3). Features (a)-(c) ensure that the claim is functionally limited to this technical purpose by specifying the mathematical model used in the simulation and how the generated noise vector y is used in it, i.e. they establish the link between the stated purpose of the method and steps (d1)-(d3). Furthermore, the mathematical model specified by features (a)-(c) defines how the numerical simulation is performed and thus also contributes to the above-mentioned technical purpose. As a result, all the steps relevant to the circuit simulation, including the mathematically expressed claim features (d1)-(d3), contribute to the technical character of the method to the extent that they are relevant for circuit simulation.

Step (ii): Document D1, which discloses a method for numerical simulation of the performance of an electronic circuit subject to 1/f noise with steps (a)-(c) but with a different mathematical algorithm for generating the 1/f-distributed random numbers, is selected as closest prior art.

Step (iii): The difference between the methods of claim 1 and D1 is the mathematical algorithm used to generate the vector of 1/f-distributed random numbers, i.e. steps (d1)-(d3). The algorithm defined by steps (d1)-(d3) requires less computer resources than that used in D1. In the context of the claimed method, this results directly in a reduction of the computer resources required for the numerical simulation of the performance of an electronic circuit subject to 1/f noise, which is the technical effect achieved over D1.

Step (iii)(c): The objective technical problem solved with respect to D1 is formulated as how to generate the 1/f-distributed random numbers used in the numerical simulation of the performance of an electronic circuit subject to 1/f noise in a manner which requires less computer resources.

Obviousness: No prior art suggests the algorithm defined by steps (d1)-(d3) as a solution to the objective technical problem. The invention as claimed is therefore considered to involve an inventive step.

Remarks: This example illustrates the situation addressed in G‑VII, 5.4, second paragraph: features which, when taken in isolation, are non-technical, but do, in the context of the claimed invention, contribute to producing a technical effect serving a technical purpose. Such features are considered to contribute to the technical character of the invention and may therefore support the presence of an inventive step.

Note that if the claim were not limited to the numerical simulation of an electronic circuit subject to 1/f noise, the mathematical algorithm defined by steps (d1)-(d3) would not serve any technical purpose and would thus not be considered to contribute to the technical character of the claim (requiring less computer resources than another mathematical algorithm being on its own not sufficient in this respect; see G‑II, 3.3).

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