United States Court of Appeals 

for the Federal Circuit ______________________ 

POWER INTEGRATIONS, INC.,

Plaintiff-Appellee

v.

FAIRCHILD SEMICONDUCTOR INTERNATIONAL, 

INC., FAIRCHILD SEMICONDUCTOR 

CORPORATION, FAIRCHILD (TAIWAN) 

CORPORATION,

Defendants-Appellants

______________________ 

2016-2691, 2017-1875

______________________ 

Appeals from the United States District Court for the 

Northern District of California in No. 3:09-cv-05235-

MMC, Judge Maxine M. Chesney.

______________________ 

Decided: July 3, 2018 

______________________ 

 FRANK SCHERKENBACH, Fish & Richardson, PC, 

Boston, MA, argued for plaintiff-appellee. Also represented by CRAIG E. COUNTRYMAN, JOHN WINSTON 

THORNBURGH, San Diego, CA; MICHAEL R. HEADLEY,

HOWARD G. POLLACK, Redwood City, CA.

 KATHLEEN M. SULLIVAN, Quinn Emanuel Urquhart & 

Sullivan, LLP, New York, NY, argued for defendantsappellants. Also represented by JOSHUA L. SOHN, Wash-
2 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

ington, DC; KEVIN ALEXANDER SMITH, San Francisco, CA; 

BLAIR MARTIN JACOBS, STEPHEN BLAKE KINNAIRD,

CHRISTINA ANN ONDRICK, PATRICK STAFFORD, Paul Hastings LLP, Washington, DC.

______________________ 

Before DYK, CLEVENGER, and CHEN, Circuit Judges.

DYK, Circuit Judge. 

Power Integrations, Inc. owns U.S. Patent Nos. 

6,212,079 (“the ’079 patent”) and 6,538,908 (“the ’908 

patent”). Power Integrations sued Fairchild Semiconductor Corporation and Fairchild (Taiwan) Corporation 

(collectively “Fairchild”) for infringement. A jury found 

Fairchild literally infringed claims 31, 34, 38, and 42 of 

the ’079 patent and infringed claims 26 and 27 of the ’908 

patent under the doctrine of equivalents. In a second trial, 

a jury awarded damages of roughly $140 million, finding 

that the entire market value rule applied in calculating 

damages for infringement of the ’079 patent. The district 

court denied Fairchild’s motions for judgment as a matter 

of law. Fairchild appeals. 

We affirm the district court’s judgments of infringement. We conclude that the entire market value rule 

cannot be used here to calculate damages. We vacate the 

damages award and remand for further proceedings. 

BACKGROUND

I 

Power Integrations and Fairchild are both manufacturers of power supply controller chips. Power supply 

controller chips are integrated circuits used in power 

supplies, such as chargers for electronic devices. These 

power supplies transform alternating current (“AC”) 

electricity, which comes from an AC outlet, into direct 
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 3

current (“DC”) electricity, which is needed to power cell 

phones, laptops, and other electronic devices. 

After AC electricity has been converted to DC electricity, a switching regulator directs the transistor in the 

circuit when to turn on and off in order to provide the 

desired amount of power to the electronic device. The 

electronic device is referred to as the “DC output” because 

it receives the DC current. The transistor turns on and off 

at defined intervals. For example, if there is a need for 

power at the DC output, the switching regulator will 

direct the transistor to stay “on” for a longer period of 

time so more power will flow to the DC output. 

The controversy here involves the ’079 and ’908 patents owned by Power Integrations. The asserted claims

of the ’079 patent cover switching regulators. Prior-art 

switching regulators were inefficient during periods when 

the DC output required little power. During these low 

power periods, prior-art switching regulators would skip 

on/off cycles to decrease the DC power provided; the 

power remained off during the skipped cycle. However, 

skipping cycles created loud noise and delivered power in 

an intermittent fashion. The ’079 patent addressed this 

problem by reducing the frequency of on/off cycles rather 

than by skipping cycles altogether. The frequency of on/off 

cycles is determined by feedback signals. Thus, the 

switching frequency varies based on the feedback signal. 

However, for a certain range of feedback signals, the 

frequency of the on/off cycles does not change. Each of the 

asserted claims requires a “fixed switching frequency for a 

first range of feedback signals.” 

The ’908 patent covers a “power supply controller,” 

which is an integrated circuit that can perform a variety 

of power-regulation functions. ’908 pat., col. 1, ll. 32–33, 

52–60. Each of the asserted claims requires a power 

supply controller comprising “a multi-function circuit
4 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

coupled to receive a signal at a multi-function terminal for 

adjusting a current limit of a power switch.” Id., col. 25, l. 

63–col. 26, l. 14. The current limit is a value of current 

that can be used by the circuit to turn off the power 

switch when the amount of current passing through the 

power switch reaches the threshold value. 

II

Power Integrations filed suit against Fairchild, alleging infringement of various claims of the ’079 patent and 

the ’908 patent.1 In February and March 2014, the district 

court held a sixteen-day jury trial. The jury found 

Fairchild literally infringed claims 31, 34, 38, and 42 of 

the ’079 patent and infringed claims 26 and 27 of the ’908 

patent under the doctrine of equivalents.2 The jury 

awarded Power Integrations $105 million in reasonable 

royalty damages. Fairchild sought judgment as a matter 

of law that it did not infringe claims of the ’079 or ’908 

patents, or in the alternative a new trial, which the 

district court denied. 

 

1 Fairchild counterclaimed for infringement of U.S. 

Patent No. 5,747,977. The jury found that Power Integrations did not infringe this patent, and the district court 

entered judgment consistent with the jury verdict. This 

aspect of the judgment has not been appealed. 

2 All of the asserted claims in this proceeding have 

been found unpatentable in two IPR proceedings. Those 

proceedings are currently pending on appeal to this court. 

See Semiconductor Components Indus., LLC v. Power 

Integrations, Inc., IPR No. 2016-00809 (P.T.A.B. Dec. 22, 

2017), appeal filed No. 18-1607 (Fed. Cir. Feb. 26, 2018); 

Semiconductor Components Indus., LLC v. Power Integrations, Inc., IPR No. 2016-00995 (P.T.A.B. Dec. 21, 2017),

appeal filed No. 18-1602 (Fed. Cir. Feb. 23, 2018).
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 5

Six months after the jury verdict, and while the case 

was still pending in the district court, our court decided

VirnetX, Inc. v. Cisco Systems, Inc., 767 F.3d 1308, 1329

(Fed. Cir. 2014), which concerned the general rule that a 

patentee seeking damages based on an infringing product 

with both patented and unpatented features must “apportion damages only to the patented features.” VirnetX

explained that simply identifying the smallest salable 

unit is not necessarily sufficient to satisfy a patentee’s 

obligation to apportion for multi-component products with 

significant unpatented features. Id. Because Power Integrations’ royalty calculation in the first trial did not 

apportion beyond the “smallest salable unit” and Power 

Integrations had disclaimed reliance on the entire market 

value rule, the district court granted a new trial on the 

issue of damages in light of VirnetX. 

The district court held a second damages trial in December 2015. The district court granted a Daubert motion 

to exclude Power Integrations’ expert testimony based on 

apportionment, but allowed its expert to present testimony based on the entire market value rule. The jury 

awarded $139.8 million in damages, based on damages 

testimony that relied solely on the entire market value 

rule. Fairchild then moved for judgment as a matter of 

law, or in the alternative a new trial, arguing that the 

damages award was not supported by substantial evidence and that the use of the entire market value rule 

was improper. The district court denied this motion. 

Fairchild now appeals the determination of literal infringement of the ’079 patent, the determination of infringement under doctrine of equivalents of the ’908 

patent, and the damages award. We have jurisdiction 

pursuant to 28 U.S.C. § 1295(a)(1). 
6 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

DISCUSSION 

I 

We first address infringement of the ’079 patent. The 

key issue here is whether the accused products have a 

“fixed switching frequency for a first range of feedback 

signal values.”3 On appeal, Fairchild does not dispute that 

 

3 Claim 31, which is representative, reads in full: 

31. A switching regulator, comprising: a power 

switch coupled between first and second terminals, the first terminal to be coupled to an energy 

transfer element of a power supply and the second 

terminal to be coupled to a supply rail of the power supply, and 

a control circuit coupled to a third terminal and 

the power Switch, the third terminal to be coupled 

to an output of the power supply, the control circuit coupled to generate a feedback signal responsive to the output of the power supply, the control 

circuit coupled to switch the power switch in response to the feedback signal, the control circuit 

coupled to switch the power switch at a fixed 

switching frequency for a first range of feedback 

signal values, the control circuit coupled to vary a 

switching frequency of the power switch without 

skipping cycles in response to the feedback signal 

for a second range of feedback signal values, 

wherein the control circuit comprises:

a feedback signal circuit coupled to the third terminal, the feedback signal circuit coupled to generate the feedback signal; and 

a pulse width modulator circuit coupled to switch 

the power switch in response to the feedback signal, 
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 7

the other claim limitations were satisfied. The jury found 

that all accused products infringed the asserted claims, 

and the district court denied judgment as a matter of law 

of no infringement. We review the denial of a motion for 

judgment as a matter of law de novo. We review a jury 

determination of infringement for substantial evidence. 

In a Markman order, the district court construed 

“fixed switching frequency” to mean “[a] non-varying 

number of switching cycles per second.” J.A. 2142. On 

appeal, Fairchild disputes: (1) whether all accused products include a “fixed” switching frequency because the 

frequency varies due to operating conditions, and 

(2) whether a particular subset of accused products, 

known as “frequency-hopping” products, has a “fixed” 

frequency. This second issue turns primarily on claim 

construction—whether the district court properly construed “fixed frequency” to include a per second limitation. But Fairchild contends that even if the claim 

construction were correct, there was not substantial 

evidence to support the jury verdict. 

Claim terms are given their ordinary and customary 

meaning, which is the meaning the term would have to a 

person of ordinary skill in the art at the time of the invention. Phillips v. AWH Corp., 415 F.3d 1303, 1312–13 (Fed. 

Cir. 2005) (en banc). We review claim construction de 

novo, except for subsidiary facts based on extrinsic evi-

 

wherein the first and second ranges of the feedback signal correspond to first and second ranges 

of on-time values of a drive signal generated by 

the pulse width modulator circuit to switch the 

power switch.

’079 patent, Ex Parte Reexamination Certificate, col. 2, 

ll. 4–32. 
8 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

dence, which we review for clear error. Teva Pharms. 

USA, Inc. v. Sandoz, Inc., 135 S. Ct. 831, 841 (2015). 

A 

Fairchild argues that the jury verdict is not supported 

by substantial evidence because none of the Fairchild 

products has a “fixed switching frequency” according to

the language of the claims or a “non-varying frequency” 

under the district court’s claim construction, because even 

during “fixed” frequency mode, the products operate with 

5% to 15% variance in frequency. This variance is due to 

operating conditions, such as temperature and input 

voltage. The question is whether this variability renders 

the products non-infringing. 

Fairchild argues that the term “fixed” under the district court’s construction of “non-varying number of 

switching cycles per second” requires an absolutely fixed 

frequency with no variance, even due to operating conditions. The district court, Fairchild asserts, rejected a 

construction of “fixed” frequency that permits natural 

variation when it rejected Power Integration’s proposed 

construction of “fixed switching frequency” as “the target 

switching frequency is intended to be substantially fixed.” 

J.A. 2125. Rather, the court adopted “fixed” as meaning 

“non-varying.” J.A. 2142.4 

 

4 Fairchild also argues that the term “fixed” cannot 

include any variations due to operating conditions based 

on statements made by Power Integrations during the 

reexamination about a particular prior art reference, the

Zhou reference. However, this argument is waived because Fairchild did not raise the prosecution history 

concerning the Zhou prior art as a claim construction 

argument before the district court. Moreover, the Zhou 

reference did not disclose holding frequency constant over 
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 9

Fairchild’s argument is unpersuasive. The district 

court’s construction of “fixed switching frequency” as 

“non-varying” does not exclude the possibility of natural 

variation because doing so would impermissibly render 

the claims inoperable. See Ecolabs, Inc. v. FMC Corp., 569 

F.3d 1335, 1345 (Fed. Cir. 2009) (finding that where claim 

language permits an operable construction, the inoperable 

construction is wrong).5 Here, the parties offered expert 

testimony to address the knowledge of persons of ordinary 

skill in the art. The expert testimony demonstrated that

no real-world power supply controllers could operate with 

an absolutely fixed, or non-varying, frequency. Indeed, 

Fairchild seems to concede that there is always some 

variation in frequency due to operating conditions. Moreover, technical marketing documents from products sold 

by Fairchild, Power Integrations, and third parties label 

these controllers as “fixed frequency” products despite the 

undisputed, minor variations in frequency. Since the term

“fixed” is not unambiguously defined in the claims, the 

fact that power supply controllers cannot operate without 

any variation supports that the plain and ordinary meaning of “fixed” encompasses minor environmental variations.

 

a range of feedback signals but instead varied frequency 

over the entire range of operation. Therefore, the prosecution history statement describing Zhou as not containing 

a “fixed” frequency was not directed to determining 

whether the switching frequency has been fixed when 

environmental variations occur while holding a fixed 

frequency over a certain range of signals.

5 This case is unlike that in Chef America, Inc. v. 

Lamb-Weston, Inc., where the claims were unambiguously 

written in a manner that rendered them inoperable. 359 

F.3d 1371, 1374 (Fed. Cir. 2004). 
10 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

Thus, the jury could have properly concluded that the 

terms “fixed frequency” and “non-varying” left open the 

possibility for minor frequency variations due to operating 

conditions. A reasonable jury could have found that the 

accused products have a “fixed” or “non-varying” frequency despite slight variance due to operating conditions. 

B 

Fairchild alternatively argues that there was no basis 

for finding that the “fixed” frequency limitation was 

satisfied for a subset of the accused products because the 

Fairchild “frequency-hopping” products intentionally vary 

frequency in order to reduce electromagnetic interference. 

The intentional varying of frequency is referred to as 

“jittering.” For example, one Fairchild frequency-hopping 

product jittered its switching frequency from 62 kilohertz 

to 68 kilohertz, around a center frequency of 65 kilohertz. 

Even though the frequency varies in any given microsecond interval, the average number of cycles per second is 

65,000. 

On appeal, Fairchild argues that the district court 

erred in construing “fixed switching frequency” as a “nonvarying number of switching cycles per second” rather 

than looking to overall variation. 

The district court construed claim terms in a series of 

Markman orders in 2011 and 2012—two years before 

trial. Power Integrations proposed that “fixed switching 

frequency” be construed to mean “the target switching 

frequency is intended to be substantially fixed; but does 

not preclude the presence of a frequency jittering circuit.” 

J.A. 2125. Fairchild proposed that: “the switching frequency does not vary.” Id. The district court then construed the term to mean a “non-varying number of 

switching cycles per second,” even though neither party 

requested the “per second” limitation. J.A. 2142. 
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 11

Although Fairchild later proposed further construction for other claim terms, Fairchild never objected to the 

“per second” construction and did not seek rehearing or 

supplemental construction. At trial, Fairchild did not 

object to the district court’s instructing the jury using the 

“per second” language. Even in its post-trial motion, 

Fairchild did not argue that the court’s construction was 

incorrect. The claim construction issue is argued for the 

first time on appeal. 

Power Integrations argues that because Fairchild did 

not seek additional claim construction at the district court 

and chose to litigate this issue as a factual dispute about 

infringement, Fairchild has waived its “per second” claim 

construction argument. Fairchild responds that it did not 

waive its claim construction argument because the claim 

construction it proposes now is the same as the claim 

construction it proposed during the Markman hearing, 

which did not contain the “per second” limitation. 

We have held that a party does not waive a claim construction argument by failing to object during trial when 

the construction proposed on appeal is the same as the 

construction proposed in a Markman hearing. O2 Micro 

Int’l Ltd. v. Beyond Innovation Tech. Co., 521 F.3d 1351, 

1359 (Fed. Cir. 2008); see also D’Agostino v. Mastercard 

Int’l Inc., 844 F.3d 945, 950 (Fed. Cir. 2016); In re Pabst 

Licensing Dig. Camera Patent Litig., 778 F.3d 1255, 1266 

(Fed. Cir. 2015). “When the claim construction is resolved 

pre-trial, and the patentee presented the same position in 

the Markman proceeding as is now pressed, a further 

objection to the district court’s pre-trial ruling may indeed 

have been not only futile, but unnecessary.” Cardiac 

Pacemakers, Inc. v. St. Jude Med., Inc., 381 F.3d 1371, 

1381 (Fed. Cir. 2004). However, this rule only applies 

when “issues were fully litigated and decided at the 

Markman stage of the litigation.” O2 Micro, 521 F.3d at 

1359. 
12 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

The problem for Fairchild is that the issue of the appropriate time interval over which to measure frequency 

was not fully litigated—or even raised as an issue in 

dispute—at the Markman stage of this proceeding. During the Markman proceedings, there was no dispute about 

the time interval. Neither Fairchild nor Power Integrations proposed a construction with the “per second” limitation. The district court added this limitation to the 

construction on its own without providing a clear explanation. Because the district court had not specifically addressed this issue in its claim construction order, in order 

to preserve an objection to the district court’s claim construction, Fairchild was required to raise the issue before 

submission to the jury. Yet even when this dispute arose 

at trial, Fairchild did not ask the district court to modify 

or clarify its claim construction with regard to “per second,” nor did it object to the jury instructions. Instead, 

Fairchild waited until this appeal to argue that the district court’s claim construction was erroneous.

It is well-settled that a party cannot reserve a new 

claim-construction argument for the post-trial motion 

stage of litigation. Lazare Kaplan Int’l, Inc. v. Photoscribe 

Techs., Inc., 628 F.3d 1359, 1376 (Fed. Cir. 2010); 

Broadcom Corp. v. Qualcomm Inc., 543 F.3d 683, 694 

(Fed. Cir. 2008); Hewlett-Packard Co. v. Mustek Sys., Inc., 

340 F.3d 1314, 1320 (Fed. Cir. 2003). 

The present situation is similar to Solvay S.A. v. Honeywell International, Inc., 742 F.3d 998 (Fed. Cir. 2014). 

In that case, the district court construed a claim term 

“isolating” to require removing two chemicals, HFC-245fa 

and HCl, from a chemical reaction. Id. at 1003. During 

claim construction, the parties did not raise and the 

district court did not address the issue of whether the two 

chemicals could return to the reactor after initially being 

removed. Id. at 1003–04. However, during the trial, a 

disagreement arose between the parties as to whether the 
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 13

chemicals had to be permanently removed. The parties 

argued the issue at trial, and the district court allowed 

jury instructions that did not necessarily require permanent removal. Id. at 1004. When the patentee argued on 

appeal that the proper claim construction required the 

chemicals to be permanently removed, we held that 

“[b]ecause [the patentee] failed to object to the court’s 

construction or jury instruction with respect to the term 

‘isolating,’ it waived the issue and cannot now raise novel 

arguments to redefine the scope of [the] claim.” Id. In 

particular, we noted that the patentee “did not ask the 

district court to modify the claim construction or accompanying jury instruction.” Id. By failing either to request 

that the district court modify or clarify its claim construction earlier in the litigation proceedings or to object to the 

jury instructions, Fairchild has waived this new claimconstruction argument. 

Because Fairchild has waived its “per second” claimconstruction objection, we only review whether substantial evidence supported the jury verdict under the court’s 

construction. See Lazare, 628 F.3d at 1376; HewlettPackard, 340 F.3d at 1320. Power Integrations’ expert, 

Dr. Kelley, testified that the accused products operate 

with a non-varying number of cycles per second for a 

range of operation. Dr. Kelley testified that the frequencyhopping products meet the limitation of a “non-varying 

number of switching cycles per second” because even 

though the frequency varies over microsecond intervals, 

the aggregate number of pulses would not vary over each 

one-second interval. Based on this testimony, a reasonable jury could have concluded that the accused products 

operate with a “fixed switching frequency” for a certain 

range of feedback signals under the district court’s construction. Thus, substantial evidence supports the jury’s 

verdict of infringement of the ’079 patent for all of the 

accused products. 
14 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

II

Next, we address infringement of the ’908 patent under the doctrine of equivalents. The ’908 patent is directed 

towards a power supply controller, where an integrated 

circuit can perform multiple functions within a single 

terminal. Claim 26 requires: 

26. A power supply controller circuit, comprising: 

a multi-function circuit coupled to receive a signal 

at a multi-function terminal for adjusting a current limit of a power switch, the multi-function 

circuit to generate a current limit adjustment signal in response to the signal; and 

a control circuit coupled to receive the current limit adjustment signal, the control circuit coupled to 

adjust the current limit of a current through the

power switch in response to the current limit adjustment signal. 

’908 patent, col. 25 l. 63–col. 26, l. 7 (emphasis added). 

Claim 27, the only other asserted claim, depends from 

claim 26. 

The dispute focuses on the “current limit” term. There 

is no dispute about claim construction. The district court 

construed “current limit” as “a value of current that can 

be used by the control circuit to turn off the power switch 

when the amount of current passing through the power 

switch reaches the threshold.” J.A. 2155. 

The accused products use a value of voltage, rather 

than a value of current, as the signal to implement the 

current limit, so there could not be literal infringement of 

this limitation. Fairchild moved in limine to preclude 

Power Integrations from arguing infringement under the 

doctrine of equivalents based on prosecution-history 

estoppel. Fairchild argued that prosecution-history estoppel existed because during prosecution of a related patent, 
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 15

Power Integrations explicitly distinguished voltage from 

current and therefore could not now assert voltage as an 

equivalent. The district court denied the motion in limine

because the prosecution history was for a different term 

in a different patent, allowing Power Integrations to 

argue voltage as an equivalent for monitoring current. 

At trial, Power Integrations’ expert testified that a 

value of voltage qualifies as a “value of current” because 

under Ohm’s Law, current is equal to voltage divided by 

resistance. J.A. 572–73, 901. The jury then found infringement under the doctrine of equivalents, and the 

district court denied judgment as a matter of law. On 

appeal, Fairchild argues that Power Integrations’ equivalents theory is barred by prosecution-history estoppel. 

Prosecution-history estoppel limits the application of 

the doctrine of equivalents. If a patentee surrenders 

certain subject matter during prosecution, the patentee is 

then barred from using the doctrine of equivalents to 

recover for infringement based on that same subject 

matter. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki 

Co., 535 U.S. 722, 733–34 (2002). Prosecution-history 

estoppel can occur either when the patentee makes a 

narrowing amendment to the claim or surrenders claim 

scope through argument to the patent examiner. Conoco, 

Inc. v. Energy & Envtl. Int’l, L.C., 460 F.3d 1349, 1363 

(Fed. Cir. 2006). Here there was no claim amendment, so 

Fairchild relies on argument-based estoppel. To invoke 

argument-based estoppel, the prosecution history must 

evince a “clear and unmistakable surrender of the subject 

matter.” Id. at 1364. The application of prosecutionhistory estoppel is a question of law that we review de 

novo. Intendis GMBH v. Glenmark Pharm. Inc., USA, 822 

F.3d 1355, 1365 (Fed. Cir. 2016). 

Fairchild argues for argument-based estoppel based 

on a statement that Power Integrations made during 
16 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

prosecution of U.S. Patent No. 6,462,971 (“the ’971 patent”), which is the parent to the ’908 patent and shares a 

specification. The relevant claim of the ’971 patent is 

directed to: 

[a] power supply controller circuit, comprising a 

current input circuit coupled to receive a current

representative of an input voltage, the current input circuit to generate an enable/disable signal 

when the current crosses a threshold having a 

hysteresis of greater than or equal to zero, the 

power supply controller to activate and deactivate 

the power supply in response to the enable/disable 

signal. 

’971 pat., col. 23, ll. 30–36 (emphasis added). 

The examiner rejected the claims based on the 

Agiman reference. In an effort to overcome the rejection, 

Power Integrations argued that “Agiman’s circuit monitors voltage rather than current.” J.A. 2283 (emphasis in 

original). Power Integrations then urged that “Agiman 

fails to disclose . . . a current input circuit coupled to 

receive a current representative of an input voltage, the 

current input circuit to generate an enable/disable signal 

when the current crosses a threshold.” Id. (emphases in 

original). Fairchild argues that this distinction also applies to the “current limit” term of the ’908 patent. 

To determine whether prosecution-history estoppel 

applies, “the relevant inquiry is whether a competitor 

would reasonably believe that the applicant surrendered 

the relevant subject matter.” Conoco, 460 F.3d at 1364

(quoting Cybor Corp. v. FAS Techs., Inc., 138 F.3d 1448, 

1457 (Fed. Cir. 1998), abrogated on other grounds by Teva 

Pharms. USA, Inc. v. Sandoz, Inc., 789 F.3d 1335 (Fed. 

Cir. 2015). When considering the prosecution history of a 

parent application to construe claim terms, we consider 

differences in the language and context of different 
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 17

claims. See Abtox, Inc. v. Exitron Corp., 122 F.3d 1019, 

1027 (Fed. Cir. 1997) (“[S]tatements in the parent application must be confined to their proper context and 

properly acknowledge the distinctions between . . . [the] 

claims.”). 

Here, the claim language on its face is different than 

the language of the claims to which the prosecution 

argument was directed. Claim 26 of the ’908 patent covers 

“a multi-function circuit coupled to receive a signal at a 

multi-function terminal for adjusting a current limit of a 

power switch, the multi-function circuit to generate a 

current limit adjustment signal in response to the signal.” 

’908 pat., col. 25 l. 63–col. 26, l. 7 (emphasis added). The 

current limit in the ’908 patent is externally adjustable 

and helps prevent a power switch from overloading due to 

excessive current flow. The ’971 patent, on the other 

hand, claims a “current input circuit coupled to receive a 

current representative of an input voltage, the current 

input circuit to generate an enable/disable signal when 

the current crosses a threshold.” ’971 pat., col. 23, ll. 30–

33 (emphasis added). The functions performed in the two 

patents are related but different. The ’908 patent claims 

receiving a signal to adjust the current limit, which in 

turn determines when to turn the power supply on and 

off. The ’971 patent claims receiving a signal that directly 

turns the power supply on and off. Importantly, the claim 

in the ’971 patent specifically distinguishes voltage from 

current, claiming “a current representative of an input 

voltage.” The ’908 claim, in contrast, does not distinguish 

between current and voltage within the claim. It merely 

describes a “signal” to adjust the current limit.

On appeal, Fairchild provides only a cursory argument of why the statement in the ’971 patent prosecution 

history should apply the embodiments claimed in the ’908 

patent. Fairchild failed to establish that the prosecution 

history is sufficiently clear as to create an estoppel. We 
18 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

conclude that the district court correctly determined that 

prosecution-history estoppel does not apply, and affirm 

the finding of infringement as to the asserted claims of 

the ’908 patent. 

III 

Lastly, we address damages. The jury awarded Power 

Integrations $139.8 million in the form of a reasonable 

royalty. The jury’s reasonable royalty covered the three 

types of losses Power Integrations’ damages expert Dr. 

Putnam testified the parties would anticipate during a 

hypothetical negotiation: lost sales, reduction in price due 

to competition, and lost licensing fees. The district court 

denied Fairchild’s motion for judgment as a matter of law 

or in the alternative a new trial with respect to damages. 

We agree with Fairchild that the district court should 

have granted the new trial motion. 

A patentee is only entitled to a reasonable royalty attributable to the infringing features. The patentee “must 

in every case give evidence tending to separate or apportion the defendant’s profits and the patentee’s damages 

between the patented feature and the unpatented features.” Garretson v. Clark, 111 U.S. 120, 121 (1884). In 

accordance with Garretson, we have required that royalties be apportioned between the infringing and noninfringing features of the product. Ericsson, Inc. v. D-Link 

Sys., Inc., 773 F.3d 1201, 1226–27 (Fed. Cir. 2014); VirnetX, 767 F.3d at 1326; Uniloc USA, Inc. v. Microsoft 

Corp., 632 F.3d 1292, 1318 (Fed. Cir. 2011); Lucent 

Techs., Inc. v. Gateway, Inc., 580 F.3d 1301, 1336–37 

(Fed. Cir. 2009). “As a substantive matter, it is the ‘value 

of what was taken’ that measures a ‘reasonable royalty’ 

under 35 U.S.C. § 284.” Ericsson, 773 F.3d at 1226 (quoting Dowagiac Mfg. v. Minn. Moline Plow Co., 235 U.S. 

641, 648 (1915)). And in the context of a utility patent, it 

is only the patented technology that is taken from the 
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 19

owner, so the value to be determined is only the value 

that the infringing features contribute to the value of an 

accused product. Id. 

Undertaking an apportionment analysis where reasonable royalties are sought generally requires a determination of the royalty base to which the royalty rate will 

be applied. We have articulated that, where multicomponent products are accused of infringement, the 

royalty base should not be larger than the smallest salable unit embodying the patented invention. We have 

cautioned against reliance on use of the entire market 

value of a multi-component product that includes a patented component because it “cannot help but skew the 

damages horizon for the jury, regardless of the contribution of the patented component to this revenue.” Uniloc, 

632 F.3d at 1320. “Where small elements of multicomponent products are accused of infringement, calculating a royalty on the entire product carries a considerable 

risk that the patentee will be improperly compensated for 

non-infringing components of that product.” LaserDynamics, 694 F.3d at 67. Admission of evidence of the entire

market value “only serve[s] to make a patentee’s proffered 

damages amount appear modest by comparison, and to 

artificially inflate the jury’s damages calculation beyond 

that which is ‘adequate to compensate for the infringement.’” Id. at 68 (quoting 35 U.S.C. § 284). Even when a 

damages theory relies on the smallest salable unit as the 

basis for calculating the royalty, the patentee must estimate what portion of that smallest salable unit is attributable to the patented technology when the smallest 

salable unit itself contains several non-infringing features. VirnetX, 767 F.3d at 1327.

The damages verdict here rests on Power Integrations’ reliance on a demanding alternative to our general 

rule of apportionment, the entire market value rule. Id. 

“The entire market value rule allows for the recovery of 
20 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

damages based on the value of an entire apparatus containing several features, when the feature patented 

constitutes the basis for consumer demand.” Lucent 

Techs., Inc. v. Gateway, Inc., 580 F.3d 1301, 1336 (Fed. 

Cir. 2009); see also Rite-Hite Corp. v. Kelley Co., 36 F.3d 

1538, 1549 (Fed. Cir. 1995) (en banc). As we have explained, “[t]he law requires patentees to apportion the 

royalty down to a reasonable estimate of the value of its 

claimed technology,” unless it can “establish that its 

patented technology drove demand for the entire product.” 

VirnetX, 767 F.3d at 1329. “[S]trict requirements limiting 

the entire market value exception ensure that a reasonable royalty ‘does not overreach and encompass components not covered by the patent.’” Id. at 1326 (quoting 

LaserDynamics, 694 F.3d at 70). 

If the product has other valuable features that also 

contribute to driving consumer demand—patented or 

unpatented—then the damages for patent infringement

must be apportioned to reflect only the value of the patented feature. This is so whenever the claimed feature 

does not define the entirety of the commercial product. In 

some circumstances, for example, where the other features are simply generic and/or conventional and hence of 

little distinguishing character, it may be appropriate to 

use the entire value of the product because the patented 

feature accounts for almost all of the value of the product 

as a whole. See AstraZeneca AB v. Apotex Corp., 782 F.3d 

1324, 1338–40 (Fed. Cir. 2015). 

Power Integrations’ royalty rate is premised on the 

’079 patent’s frequency reduction feature as driving 

consumer demand for Fairchild’s controller chips. To 

support this contention, Power Integrations provided 

evidence that the ’079 patented frequency reduction 

feature was essential to many customers, as it allowed the 

products to meet the federal government’s Energy Star 

program. In addition, Power Integrations provided evi-
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 21

dence that some customers asked for the ’079 feature, 

that products with the ’079 feature outsold other products, and that technical marketing materials promoted 

the ’079 feature. Both parties, however, agreed that the 

accused products contained other valuable features as 

well. Power Integrations presented no evidence about the 

effect of those features on consumer demand or the extent 

to which those features were responsible for the products’ 

value. Power Integrations did not seek a separate jury 

determination as to damages for infringement of the 

asserted claims of the ’908 patent, and it is clear that the 

jury calculated damages only for the ’079 patent. 

In its JMOL motion, Fairchild argued that the evidence presented by Power Integrations was insufficient as 

a matter of law to invoke the entire market value rule, 

pointing to our decision in LaserDynamics. The district 

court noted that three prior cases relied on evidence that 

“LaserDynamics . . . arguably would find inadequate to 

support EMVR,” and that the evidence presented by 

Power Integrations was comparable to the evidence in the 

prior cases. J.A. 26; see Bose Corp. v. JBL, Inc., 274 F.3d 

1354, 1361 (Fed. Cir. 2001); Tec Air, Inc. v. Denso Mfg. 

Mich. Inc., 192 F.3d 1353, 1362 (Fed. Cir. 1999); Fonar 

Corp. v. Gen. Elec. Co., 107 F.3d 1543, 1552–53 (Fed. Cir. 

1997). 

Despite the district court’s suggestion to the contrary, 

there is no conflict between LaserDynamics and these 

earlier cases, and subsequent cases have relied on LaserDynamics. See VirnetX, 767 F.3d at 1326–27; Commonwealth Sci. & Indus. Research Org. v. Cisco Sys., Inc., 

809 F.3d 1295, 1301–02 (Fed. Cir. 2015); Versata Software, Inc. v. SAP Am., Inc., 717 F.3d 1255, 1268 (Fed. Cir. 

2013). LaserDynamics discussed how a patentee can 

prove that a patented feature forms the basis for consumer demand in the context of multi-component products. 

There we explained that “[i]t is not enough to merely 
22 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

show that the [patented feature] is viewed as valuable, 

important, or even essential to the use of the [infringing 

product].” LaserDynamics, 694 F.3d at 68. Moreover, 

“proof that consumers . . . choose the [infringing product] 

having the [patented] functionality says nothing as to 

whether the presence of that functionality is what motivates customers to buy [an infringing product] in the first 

place.” Id. None of the earlier cases that the district court 

cited discussed other valuable features that made the 

application of the entire market value rule inappropriate. 

See Bose, 274 F.3d at 1361; Tec Air, 192 F.3d at 1362; 

Fonar, 107 F.3d at 1552–53. These cases merely considered whether a patented feature formed the basis for 

consumer demand and do not conflict with the legal test 

articulated in LaserDynamics, which is binding. 

As LaserDynamics, Versata, and VirnetX held, the entire market value rule is appropriate only when the 

patented feature is the sole driver of customer demand or 

substantially creates the value of the component parts.

LaserDynamics, 694 F.3d at 67; Versata, 717 F.3d at 

1268; VirnetX, 767 F.3d at 1326. The burden of proof in 

this respect is on the patent holder. LaserDynamics, 694

F.3d at 67. The question is whether the accused product, 

compared to other products in the same field, has features 

that would cause consumers to purchase the products 

beyond the patented feature, i.e., valuable features. 

Where the accused infringer presents evidence that its 

accused product has other valuable features beyond the 

patented feature, the patent holder must establish that 

these features are not relevant to consumer choice. A 

patentee may do this by showing that the patented feature “alone motivates customers to purchase [the infringing product]” in the first place. See id. at 69. But when the 

product contains multiple valuable features, it is not 

enough to merely show that the patented feature is 

viewed as essential, that a product would not be commer-
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 23

cially viable without the patented feature, or that consumers would not purchase the product without the 

patented feature. Id. at 68. When the product contains 

other valuable features, the patentee must prove that 

those other features did not influence purchasing decisions.

Here, the power supply controllers had other valuable

features, such as jittering. The district court noted that 

“there is evidence in the record that other features are 

important and are highlighted by the respective parties” 

and that “there is no question that . . . there are other 

valuable features.”6 J.A. 1764. In fact, Power Integrations 

sought infringement damages from Fairchild on the 

jittering feature in these same products in a separate 

lawsuit based on different patents, and we affirmed the 

judgment of infringement. See Power Integrations, Inc. v. 

Fairchild Semiconductor Int’l, Inc., 843 F.3d 1315 (Fed. 

Cir. 2016). Moreover, many of Fairchild’s technical marketing documents specifically mention the jittering feature and other features in addition to the ’079 patented 

feature. There is no proof that these features, including 

jittering, did not affect consumer demand. Without such 

proof, Power Integrations did not meet its burden to show 

that the patented feature was the sole driver of consumer 

demand, i.e., that it alone motivated consumers to buy the 

accused products.7 

 

6 Moreover, in an order denying a permanent injunction, the district court noted that the circuits “contain 

numerous features aside from the patented features.” J.A. 

2293. 

7 Power Integrations provided testimony that the 

patented feature drove demand for the purchase of some 

products. This evidence almost entirely concerned Power 

Integrations’ own products, TOPSwitch-Fx and 
24 POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR

Because the evidence presented by Power Integrations was insufficient as a matter of law to invoke the 

entire market value rule, we vacate the award of damages 

and remand for a new trial. In light of this disposition, we 

need not address Fairchild’s other arguments about the 

sufficiency of the reasonable-royalty evidence. 

CONCLUSION

We affirm the judgment of infringement of the asserted claims of the ’079 and the ’908 patents. We vacate the 

damages award and remand for further proceedings 

consistent with this opinion. 

AFFIRMED-IN-PART, VACATED-IN-PART, 

REMANDED

 

TOPSwitch-Gx, not Fairchild’s. Power Integrations contends that the only difference between the older 

TOPSwitch-Fx and the newer TOPSwitch-Gx controller 

chips is the frequency reduction feature covered by the 

’079 patent, and that the frequency reduction feature was 

the reason why its customers would buy the Gx product 

over the Fx product. We, however, explained in LaserDynamics that such a comparator, without more, is not 

enough to prove that the frequency reduction feature 

alone drives consumer demand for power supply controller chips. 694 F.3d at 68 (“Put another way, if given a 

choice between two otherwise equivalent laptop computers, only one of which practices optical disc discrimination, proof that consumers would choose the laptop 

computer having the disc discrimination functionality 

says nothing as to whether the presence of that functionality is what motivates consumers to buy a laptop computer in the first place. It is this latter and higher degree 

of proof that must exist to support an entire market value 

rule theory.”). Moreover, this evidence does not address 

the other valuable features in Fairchild’s products. 
POWER INTEGRATIONS, INC. v. FAIRCHILD SEMICONDUCTOR 25

COSTS

Costs to neither party.