HTC Corporation v Nokia Corporation

A patent claim must be construed according to its language and the understanding of the skilled person in context. A circuit capable of operating as a modulator is not necessarily a modulator for novelty purposes; its function depends on the surrounding circuitry and intended use. An inherent parasitic effect does not satisfy a claim requiring an additional low-pass filter arrangement. For obviousness, the skilled person must read the prior art properly and without hindsight. Extracting part of a prior-art solution and applying it to a different problem will not be obvious merely because the resulting modification can be described. A purchaser from a licensee acquires no broader patent rights than the licensee possessed, absent agreement to that effect.

Nokia alleged that HTC had infringed European Patent (UK) No 0 998 024, concerning a modulator structure for a transmitter and mobile station. HTC denied infringement, pleaded that its products were licensed, and challenged validity on novelty and obviousness grounds over Itakura and Tan.

The dispute concerned the construction of claim 1, the disclosure and obviousness of the claimed modulator architecture, infringement by representative HTC devices, and whether HTC acquired a licence through its purchase of Qualcomm chips under an agreement between Nokia and Qualcomm.

1. Construction. A modulator was construed in accordance with the Patent’s definition as an arrangement in which the information signal and carrier-frequency signal interact. Whether a circuit is a modulator depends on context, including the surrounding circuitry. Claim 1 required a modulator containing switching and driver arrangements, but did not require the driver arrangement to form part of the Gilbert cell. A driver arrangement was a circuit converting a differential voltage input into a differential current signal. The claimed low-pass filter had to be an additional arrangement, rather than the inherent filtering effect of parasitic capacitance. The requirement that it filter the information signal before mixing was a functional requirement.
2. Validity. Itakura disclosed a multiplier, not a modulator, and did not disclose filtering of the information signal before mixing because its low- and high-frequency components were recombined before mixing. The inherent capacitance of its current mirrors did not satisfy the filter limitation. Claim 1 was therefore novel. Tan concerned voltage-to-current conversion and anti-aliasing before analogue-to-digital conversion, not modulators, transmitters or mobile phones.
3. Obviousness. Applying the structured approach in Pozzoli v BDMO SA [2007] EWCA Civ 588, the skilled person would understand that Itakura’s low-pass filter and feed-forward path operated together to improve high-frequency operational speed. Arriving at the invention required extracting only part of that solution and applying it to a different problem. That was a classic application of hindsight. Tan was directed to a different problem and would not be regarded as relevant. Claim 1 was not obvious over either document. Claims 6 and 7 did not require separate consideration.
4. Infringement. The representative devices used Gilbert-cell modulators with driver arrangements including the relevant transistors and low-pass filters. A Gilbert cell could be constructed with four transistors and appropriate surrounding circuitry. The low-pass filter formed part of the current mirror, driver arrangement and modulator. Claims 1, 6 and 7 were infringed.
5. Licence. Under section 60(1) of the Patents Act 1977, HTC required Nokia’s consent to the relevant acts. Under the Betts v Willmott principle, a purchaser from a patentee may receive an implied licence, but a purchaser from a licensee cannot acquire rights exceeding those granted to the licensee. The Qualcomm agreement did not extend to the circumstances of the case. US Federal patent exhaustion law did not form part of Delaware contract law for interpreting the agreement concerning non-US patents. In any event, the chips were sold in Taiwan, not the USA, so the exhaustion defence failed.

First-instance decision in the High Court (Patents Court). No prior appellate decision was stated in the judgment.