Opinion ID: 856284
Heading Depth: 2
Heading Rank: 1

Heading: frequency variation signal

Text: The district court construed the term “frequency variation signal” in the ’851 and ’366 Patents as “an internal signal that cyclically varies in magnitude during a fixed period of time and is used to modulate the frequency of the oscillation signal within a predetermined frequency range.” On appeal, Fairchild argues that the district court erred by improperly reading features of the preferred embodiments into the claims. Specifically, Fairchild argues that the claimed “frequency variation signal” is not limited to an internal signal (the “internal signal” limitation) and that “frequency variation signal” is not limited to a signal that varies cyclically in magnitude during a fixed period of time (the “cyclically varies” limitation). These limitations, Fairchild insists, appear in the patents’ preferred embodiments and not in the claims, and because the district court’s construction incorporates both limitations, that construction is incorrect as a matter of law. Fairchild argues that we should not look to the patent specification to define the disputed term “frequency variation signal” because the term has a plain and ordinary meaning. Fairchild would have us construe “frequency variation signal” more broadly as “a signal that is used to vary the frequency of the oscillation signal.” Power Integrations argues that the district court correctly construed “frequency variation signal.” Power Integrations argues that “frequency variation signal” does not have a plain and ordinary meaning. Because we must consider claim terms in light of the entire patent, Power Integrations insists that we must look to the specification to define “frequency variation signal.” Power Integrations argues that, although the claims do not explicitly recite POWER INTEGRATIONS v. FAIRCHILD SEMI 16 the “internal signal” and “cyclically varies” limitations, these limitations are necessary and inherent components of the term “frequency variation signal.” Power Integrations further argues that failing to include the “internal signal” limitation would cause the claims to read on the prior art, and would likewise ignore a fundamental aspect of the invention’s improvement. With respect to the “cyclically varies” limitation, Power Integrations maintains that all examples and descriptions in the patents limit the “frequency variation signal” to a “signal that cyclically varies in magnitude during a fixed period of time.” Without this limitation, Power Integrations argues, the invention would experience the same problem with “unpredictably, externally influenced variations the patent set out to solve.” Power Integrations urges that the district court correctly construed the claims to uphold their validity, as required by our precedent. In construing a claim term, we look to the words of the claim itself. Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed. Cir. 1996). If the claim term has a plain and ordinary meaning, our inquiry ends. Id. If, however, the claim term does not have an ordinary meaning, and its meaning is not clear from a plain reading of the claim, “we turn to the remaining intrinsic evidence, including the written description, to aid in our construction of that term.” Telemac Cellular Corp. v. Topp Telecom, Inc., 247 F.3d 1316, 1326 (Fed. Cir. 2001). As we have said, “the specification is always highly relevant to the claim construction analysis. Usually, it is dispositive; it is the single best guide to the meaning of a disputed term.” Vitronics, 90 F.3d at 1582. The construction that stays true to the claim language and most naturally aligns with the patent’s description of the invention will be, in the end, the correct construction. Renishaw PLC v. 17 POWER INTEGRATIONS v. FAIRCHILD SEMI Marposs Societa’ per Azioni, 158 F.3d 1243, 1250 (Fed. Cir. 1998). With these principles in mind, we turn to the claims of the ’851 and ’366 Patents. Claim 1 of the ’851 Patent recites both a frequency variation circuit that provides a frequency variation signal and an oscillator that provides an oscillation signal having a frequency range, said frequency of said oscillation signal varying within said frequency range according to said frequency variation signal. ’851 Patent col. 12 ll. 22–27 (emphases added). Similarly, claim 14 of the ’366 Patent includes a frequency variation circuit that provides a frequency variation signal and wherein said maxi- mum time period varies according to a magnitude of said frequency variation signal. ’366 Patent col. 14 ll. 14–17 (emphases added). Claims 1 and 14 do not further define “frequency variation signal.” Although Fairchild argues that “frequency variation signal” has a plain and ordinary meaning, an expert for Power Integrations, Mr. Blauschild, testified that “[t]he term ‘frequency variation signal,’ recited in the ’851 Patent, is not a term of art.” “Nor would this term have had,” Mr. Blauschild continued, “a plain and ordinary meaning to one of skill in the art at the time of the invention.” J.A. 359. Turning to the specification, Mr. Blauschild opined that “the specification of the ’851 POWER INTEGRATIONS v. FAIRCHILD SEMI 18 Patent clearly defines such a signal as an internal signal that cyclically varies in magnitude during a fixed period of time.” Id. Fairchild offers no evidence to contradict the testimony of Mr. Blauschild other than its own assertion that “frequency variation signal” has a plain and ordinary meaning. We are not persuaded that the claims inform a plain and ordinary meaning of the term “frequency variation signal,” nor do we agree with Fairchild that we need only a dictionary to discern the meaning of “frequency variation signal.” Unless the inventor intended a term to cover more than the ordinary and customary meaning revealed by the context of the intrinsic record, it is improper to read the term to encompass a broader definition simply because it may be found in a dictionary, treatise, or other extrinsic source. Nystrom v. TREX Co., Inc., 424 F.3d 1136, 1145 (Fed. Cir. 2005). In any event, our inquiry here starts with the intrinsic record, including the specification, and not with a dictionary definition of the disputed term. Phillips, 415 F.3d at 1321 (“The problem is that if the district court starts with the broad dictionary definition in every case and fails to fully appreciate how the specification implicitly limits that definition, the error will systematically cause the construction of the claim to be unduly expansive.”). Here, the specification of the ’851 Patent describes the frequency variation signal: Although the presently preferred frequency variation signal 400 is a triangular waveform, alter- nate frequency variation signals such as ramp signals, counter output signals or other signals that vary in magnitude during a fixed period of time may be utilized as the frequency variation signal. 19 POWER INTEGRATIONS v. FAIRCHILD SEMI ’851 Patent col. 6 ll. 34–38 (emphases added). The patent thus contemplates frequency variation signals other than the preferred embodiment’s triangular waveform. The specification describes these alternatives as “other signals that vary in magnitude during a fixed period of time.” Id. col. 6 ll. 36–37. Specifically limiting the expansive term “other signals” to “signals that vary in magnitude during a fixed period of time” suggests that the patentee contemplated only frequency variation signals having a periodic waveform. The intrinsic record thus clearly indicates the patentee’s precise conception and formulation, which here must control our construction. See Renishaw, 158 F.3d at 1250 (“Ultimately, the interpretation to be given a term can only be determined and confirmed with a full understanding of what the inventors actually invented and intended to envelop with the claim.”). We also note that the specification, in describing the frequency variation signal, lists several specific examples followed by the general phrase “or other signals . . . .” When a general phrase follows a list of specific items, this can be a good indication that the general phrase refers to additional items of the same kind. Here, the specification lists a preferred “triangular waveform” along with two alternatives, “ramp signals” and “counter output signals.” All of these signals have periodic waveforms. ’851 Patent col. 6 ll. 35–36. Thus, in context, the general phrase “other signals” suggests other periodic signals. This implicit limitation is confirmed by the words that follow: “other signals that vary in magnitude during a fixed period of time.” Id. col. 6 ll. 36–37 (emphasis added). We thus agree with the district court that the proper construction of “frequency variation signal” includes the “cyclically varies” limitation. With regard to the “internal signal” limitation, the specification indicates that the term “frequency variation POWER INTEGRATIONS v. FAIRCHILD SEMI 20 signal” refers to an internal signal. In two separate places, the specification provides, That is, the switching frequency of the pulse width modulated switch 262 varies according to an internal frequency variation signal. This has an advantage over the frequency jitter operation of [the prior art circuit of] FIG. 1 in that the fre- quency range of the presently preferred pulse width modulated switch 262 is known and fixed, and is not subject to the line voltage or load mag- nitude variations. ’851 Patent col. 6 ll. 12–18, col. 11 ll. 44–49 (emphases added). This description confirms that the patentee contemplated a fixed-range, periodic frequency variation signal, and it further indicates that the internal character of the frequency variation signal is essential to the invention. It is the internal character of the signal that makes the frequency-jittering functionality “not subject to the line voltage or load magnitude variations.” Id. col. 6 ll. 17–18, col. 11 ll. 48–49. As the specification reflects, the patentee did not employ the term “frequency variation signal” to refer to external signals, nor did the patentee consider external frequency variation signals as part of the invention. In fact, the patentee sought to alleviate problems with the prior art’s external frequency variation techniques. For these reasons, the district court properly limited the claimed “frequency variation signal” to an internal, periodic signal. We thus conclude that the district court correctly construed “frequency variation signal” as “an internal signal that cyclically varies in magnitude during a fixed period of time and is used to modulate the frequency of the oscillation signal within a predetermined frequency range.” 21 POWER INTEGRATIONS v. FAIRCHILD SEMI