R2 Semiconductor, Inc v Intel Corporation (UK) Limited & Anor

Patent claims are construed purposively, but limitations cannot be read into them merely because the specification’s examples use a narrower arrangement. A claim requiring components to be “interleaved” may require close association sufficient to fulfil the claim’s purpose, without prescribing a particular layout unless the language does so. Novelty requires clear and unmistakable directions to do what the claim covers. Inventive step may be established where an obvious design variation would address a problem which the skilled person would recognise, even if the prior art does not expressly identify that problem. Experimental evidence must be assessed fairly and in context; a notice of experiments does not automatically confine the party’s pleaded case.

R2 alleged that Intel’s fully integrated voltage regulators infringed the UK designation of European Patent No. 3 376 653, entitled “Over voltage protection of a switching converter”. Intel counterclaimed for invalidity on grounds including lack of novelty, lack of inventive step, added matter and insufficiency. R2 conditionally proposed two alternative amendments to claim 1.

The principal issues were the construction of “voltage spike protection circuitry” and “interleaved between”, whether claim 1 was novel and inventive over the prior-art Sun paper, whether the proposed amendments were inventive, and whether representative Intel regulators satisfied the claims.

1. Construction. “Voltage spike protection circuitry” required circuitry suitable to protect the switching transistors from spikes or ringing causing a significant deleterious impact on reliability or efficiency, whether immediately or over the expected lifetime contemplated by the skilled person. Significant protection, more than insignificant protection, could suffice. “Interleaved between” required associated charge-storage and switching segments to be placed close enough to minimise connection length, subject to other design considerations. It did not require the charge-storage segments always to be physically between switching blocks.
2. Scope of claim 1. The claim was not limited to single-phase operation. Connected switching elements could operate in a multi-phase arrangement. The claim’s examples did not justify importing a limitation absent from the claim language.
3. Novelty. Applying the principle stated in General Tire & Rubber Co v Firestone Tyre & Rubber Co Ltd [1972] RPC 457, Sun disclosed connected and subdivided switching elements, charge-storage segments satisfying the construction of “interleaved”, and a dissipative element. However, Sun did not contain clear and unmistakable directions to provide voltage-spike protection within the meaning of claim 1. Claim 1 was therefore novel over Sun.
4. Inventive step. The skilled person would have recognised that the Sun prototype might be vulnerable to voltage spikes and that protection could be needed. Introducing an input decoupling capacitor as voltage-spike protection would have been an obvious variation. Claim 1 consequently lacked inventive step over Sun. The same conclusion applied to claims 1A and 1B; the added-matter issues therefore did not need to be decided.
5. Infringement. The three representative Intel FIVRs satisfied the “interleaved” requirement. On the best available model, the MIM capacitors provided modest but significant protection against spikes and associated ringing over the relevant lifetime. Had the Patent been valid, the accused FIVRs would have infringed claim 1.
6. Disposition. The Patent was invalid for lack of inventive step over Sun.