       NOTE: This disposition is nonprecedential.


  United States Court of Appeals
      for the Federal Circuit
                 ______________________

       LIGHTING BALLAST CONTROL LLC,
               Plaintiff-Appellee,
                            v.
    PHILIPS ELECTRONICS NORTH AMERICA
               CORPORATION,
                 Defendant,
                          AND
  UNIVERSAL LIGHTING TECHNOLOGIES, INC.,
             Defendant-Appellant.
                 ______________________

                       2012-1014
                 ______________________

    Appeal from the United States District Court for
the Northern District of Texas in case no. 09-CV-0029,
Judge Reed O’Connor.
                ______________________

                Decided: January 2, 2013
                 ______________________

    JONATHAN T. SUDER, Friedman, Suder & Cooke, of
Fort Worth, Texas, argued for plaintiff-appellee. With him
on the brief was ROBERT P. GREENSPOON, Flachsbart &
Greenspoon, LLC, of Chicago, Illinois.
2                      LIGHTING BALLAST   v. PHILIPS ELECTRON

    STEVEN J. ROUTH, Orrick, Herrington & Sutcliffe LLP,
of Washington, DC, argued for defendant-appellant. With
him on the brief were STEN A. JENSON, JOHN R. INGE, T.
VANN PEARCE, JR., and DIANA M. SZEGO.
                 ______________________



Before RADER, Chief Judge, O’MALLEY and REYNA, Circuit
Judges.
REYNA, Circuit Judge
    Lighting Ballast Control LLC (“Lighting Ballast”)
sued Universal Lighting Technologies, Inc. (“ULT”) for
infringement of U.S. Patent No. 5,436,529 (the ’529 Pat-
ent). The patented technology relates to control and
protection circuits for electronic lighting ballasts com-
monly used in fluorescent lighting. The district court
construed the term “voltage source means” as a means-
plus-function limitation under 35 U.S.C. § 112, ¶ 6.
Lighting Ballast Control, LLC v. Philips Elecs. N. Am.
Corp., 2010 U.S. Dist. LEXIS 127409, *26–41 (N.D. Tex.
Dec. 2, 2010). Following a jury verdict in favor of Light-
ing Ballast, the district court entered final judgment of
infringement and validity with respect to independent
claim 1 and its dependent claims 2 and 5.
    Because we find that the term “voltage source means”
in the claims of the ’529 Patent is a means-plus-function
limitation under § 112, ¶ 6, and because we find in the
specification no corresponding structure, we hold the
claims invalid for indefiniteness and reverse the judgment
of the district court.
                I. PATENTED TECHNOLOGY
    High levels of electric current are required to start a
fluorescent lamp. As a result, a fluorescent lamp fixture
typically includes an electronic ballast to regulate current
flow. The electronic ballast helps maintain a current level
 LIGHTING BALLAST   v. PHILIPS ELECTRON                  3
high enough to start the lamp while simultaneously
preventing current from reaching destructive levels.
When a lamp is removed from its holders or when a
filament is broken, current provided by the ballast sud-
denly ceases to flow though the lamp and dissipates back
into the ballast circuitry. The dissipating current can
destroy the ballast and create an electric shock hazard for
someone servicing the lamp.
    The ’529 Patent discloses an electronic ballast with a
number of improvements over the prior art, including an
ability to shield itself from destructive levels of current
when a lamp is removed or becomes defective. ’529 Pat-
ent col. 2 ll. 39–47. Claim 1 recites,
        An energy conversion device employing an os-
   cillating resonant converter producing oscilla-
   tions, having DC input terminals producing a
   control signal and adapted to power at least one
   gas discharge lamp having heatable filaments, the
   device comprising:
           voltage source means providing a constant
       or variable magnitude DC voltage between the
       DC input terminals;
          output terminals connected to the fila-
       ments of the gas discharge lamp;
           control means capable of receiving control
       signals from the DC input terminals and from
       the resonant converter, and operable to effec-
       tively initiate the oscillations, and to effec-
       tively stop the oscillations of the converter;
       and direct current blocking means coupled to
       the output terminals and operable to stop flow
       of the control signal from the DC input termi-
       nals, whenever at least one gas discharge
       lamp is removed from the output terminals or
       is defective.
4                      LIGHTING BALLAST   v. PHILIPS ELECTRON
Id. col. 11 ll. 49–68 (emphasis added). The “control
means” and the “direct current blocking means” corre-
spond generally to circuits designed to prevent current
from dissipating into the ballast circuitry when a lamp is
removed or defective. See, e.g., id. col. 7 l. 45 to col. 8 l.
45. These two elements appear to be central features of
the invention. See Joint App. 8147 (applicant describing
the “particular arrangement of control means and direct
current blocking means” as a key feature in a Response to
the PTO). The “voltage source means” provides the device
with useable DC voltage. See id.
                  II. TRIAL PROCEEDINGS
    On motion for summary judgment, ULT argued that
“voltage source means” is a means-plus-function limita-
tion and that the claims are invalid under 35 U.S.C. §
112, ¶ 2, because the specification fails to disclose any
structure capable of providing DC voltage to the device.
The district court initially agreed with ULT’s assertion
and found the asserted claims invalid for indefiniteness.
Lighting Ballast Control, LLC v. Philips Elecs. North Am.
Corp., 2010 U.S. Dist. LEXIS 85570, *29–31 (N.D. Tex.
Aug. 19, 2010).
    On motion for reconsideration, the district court re-
versed its indefiniteness decision because its initial con-
struction of “voltage source means” “exalted form over
substance and disregarded the knowledge of a person of
ordinary skill in the art.” Lighting Ballast Control, LLC
v. Philips Elecs. N. Am. Corp., 2010 U.S. Dist. LEXIS
127409, at *38 (N.D. Tex. Dec. 2, 2010). The court cited
testimony from an expert for Lighting Ballast, Dr. Rob-
erts, and the inventor, Andrew Bobel, both of whom
testified that one of skill in the art would understand the
claimed “voltage source means” to correspond to a rectifier
(which converts AC to DC) or other structure capable of
supplying useable voltage to the device. The district court
thus found that means-plus-function claiming did not
 LIGHTING BALLAST   v. PHILIPS ELECTRON                  5
apply and construed the limitation according to its “ordi-
nary meaning in the art.” The court found that, according
to the limitation’s ordinary meaning, the claimed “voltage
source means” corresponds to a class of structures: a
rectifier for common applications in which the claimed
device is used with an AC power line; and a battery or the
like for less commonly used applications in which a DC
power line is used.
    ULT again moved for summary judgment, renewing
its argument that the term “voltage source means” in-
vokes means-plus-function claiming and is indefinite.
The district court responded that it had “twice addressed
this limitation” and declined “to address the same issue a
third time.” Joint App. 62. At the close of evidence, ULT
moved for judgment as a matter of law (“JMOL”) under
FRCP 50(a), but did not continue to dispute the court’s
construction of “voltage source means.” The court denied
ULT’s JMOL motion. The district court stated in its jury
charge that the term “voltage source means” refers to “a
rectifier.” ULT did not object to this aspect of the jury
charge. After the jury found claim 1 and its dependent
claims 2 and 5 valid and infringed, ULT renewed its
JMOL motion under FRCP 50(b) but did not press its
argument regarding the court’s construction of “voltage
source means.” The district court denied ULT’s JMOL
motion and entered final judgment in favor of Lighting
Ballast.
   ULT appeals. We have jurisdiction pursuant to 28
U.S.C. § 1295(a)(1).
                        III. WAIVER
    We first address whether ULT waived the right to
dispute the district court’s construction of the term “volt-
age source means.” Lighting Ballast argues that ULT
waived its argument by failing to raise the argument in a
JMOL motion during trial or in a renewed JMOL motion
after the jury verdict, and by failing to object to the jury
6                     LIGHTING BALLAST   v. PHILIPS ELECTRON
instructions regarding the “voltage source means” limita-
tion.
    To determine whether a party waived a defense, we
look to law of the applicable regional circuit, which in this
case is the Fifth Circuit. See Ultra-Precision Mfg. v. Ford
Motor Co., 411 F.3d 1369, 1376 (Fed. Cir. 2005). In the
Fifth Circuit, “[i]t is a well-settled rule of law that an
appeal from a final judgment raises all antecedent issues
previously decided.” Exxon Corp. v. St. Paul Fire &
Marine Ins. Co., 129 F.3d 781, 784 (5th Cir. 1997).
“[O]nce a final judgment is entered, all earlier non-final
orders affecting that judgment may properly be appealed.”
Id. Thus, “a party may obtain review of prejudicial ad-
verse interlocutory rulings upon his appeal from adverse
final judgment, at which time the interlocutory rulings
(nonreviewable until then) are regarded as merged into
the final judgment terminating the action.” Dickinson v.
Auto Center Mfg. Co., 733 F.2d 1092, 1102 (5th Cir. 1983).
    This is not a situation where a party has failed to
raise an issue before the trial court that it seeks to have
us review on appeal. ULT twice moved for summary
judgment and argued its proposed construction of “voltage
source means.” In response to ULT’s second motion for
summary judgment, the district court denied the motion
and ruled that it would not “address the issue a third
time,” at which point the dispute surrounding the “voltage
source means” became fully litigated. The district court’s
final claim construction and indefiniteness ruling con-
cerned only questions of law. See Biomedino, LLC v.
Waters Techs. Corp., 490 F.3d 946, 949 (Fed. Cir. 2007)
(noting that an indefiniteness determination, like claim
construction, is a question of law). Thus, the district
court’s interlocutory ruling regarding the “voltage source
means” merged into the final judgment terminating the
action. See Dickinson, 733 F.2d at 1102.
 LIGHTING BALLAST   v. PHILIPS ELECTRON                   7
    Once ULT’s position regarding the “voltage source
means” was made clear to the district court, ULT was not
required to renew its arguments during jury instructions.
See O2 Micro Int’l Ltd. v. Beyond Innovation Tech. Co.,
521 F.3d 1351, 1359 (Fed. Cir. 2008) (“When the claim
construction is resolved pre-trial, and the patentee pre-
sented the same position in the [pre-trial] 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.”). As a result, we find that ULT preserved
its claim construction and indefiniteness argument with
respect to “voltage source means” and that the issue is
properly raised on appeal.
           IV. MEANS-PLUS-FUNCTION CLAIMING
     Means-plus-function limitations are governed by 35
U.S.C. § 112, ¶ 6, which allows a patentee to express a
claimed element as a “means or step for performing a
specified function without the recital of structure, mate-
rial, or acts in support thereof.” Such an element “shall
be construed to cover the corresponding structure, mate-
rial, or acts described in the specification and equivalents
thereof.” § 112, ¶ 6. The statute thus establishes a quid
pro quo whereby a patentee may conveniently claim an
element using a generic “means” for performing a func-
tion, provided the patentee’s specification discloses struc-
ture capable of performing that function. Atmel Corp. v.
Info. Storage Devices, Inc., 198 F.3d 1374, 1381 (Fed. Cir.
1999). Whether a claim limitation invokes means-plus-
function claiming under § 112, ¶ 6, is a matter of claim
construction and therefore a question of law that we
review without deference. See Cybor Corp. v. FAS Techs.,
Inc., 138 F.3d 1448, 1454–55 (Fed. Cir. 1998) (en banc).
    Our first step in analyzing a means-plus-function
limitation is to determine whether § 112, ¶ 6, applies.
Kemco Sales, Inc. v. Control Papers Co., 208 F.3d 1352,
1361 (Fed. Cir. 2000). We start by considering whether
8                     LIGHTING BALLAST   v. PHILIPS ELECTRON
the limitation includes the word “means,” “as the terms
‘means’ and ‘means for’ have become closely associated
with means-plus-function claiming.”      Inventio AG v.
Thyssenkrupp Elevator Ams. Corp., 649 F.3d 1350, 1356
(Fed. Cir. 2011). The word “means” triggers a presump-
tion that “the inventor used this term advisedly to invoke
[means-plus-function claiming].” York Prods., Inc. v.
Central Tractor, 99 F.3d 1568, 1574 (Fed. Cir. 1996)
(citation omitted).
    The presumption triggered by use of the word
“means” may be rebutted if the claim itself recites suffi-
cient structure for performing the function. See Cole v.
Kimberly-Clark Corp., 102 F.3d 524, 531 (Fed. Cir. 1996).
In Cole, for example, we construed a claim directed to
removable training pants for toddlers. 102 F.3d at 529.
The claim recited a “perforation means extending from
the leg band means to the waist band means through the
outer impermeable layer means for tearing the outer
impermeable layer means for removing the training brief
in case of an accident by the user.” Id. at 530. We held
that the term “perforation means” did not invoke means-
plus-function claiming because the claim described not
only the structure for performing the tearing function
(“perforation”) but also the structure’s location (extending
from the leg band to the waist band) and extent (extend-
ing through the outer impermeable layer). Id. at 531.
“An element with such a detailed recitation of its struc-
ture, as opposed to its function, cannot meet the require-
ments of [§ 112, ¶ 6].” Id.
     By contrast, when a term only indicates what the re-
cited means “does, not what it is structurally,” the claim is
properly construed under § 112, ¶ 6. Laitram Corp. v.
Rexnord, Inc., 939 F.2d 1533, 1536 (Fed. Cir. 1991). For
example, in Biomedino, we construed the phrase “control
means for automatically operating said valving.” 490
F.3d at 949. We held that the term “control” failed to
convey sufficient structure to rebut the presumption that
 LIGHTING BALLAST   v. PHILIPS ELECTRON                  9
means-plus-function claiming applied because “‘control’ is
simply an adjective describing ‘means’: it is not a struc-
ture or material capable of performing the identified
function.” Id. at 950.
    Here, because claim 1 of the ’529 Patent recites a
“voltage source means,” we start from the presumption
that means-plus-function claiming under § 112, ¶ 6,
applies. The claim goes on to recite the corresponding
function: “providing a constant or variable magnitude DC
voltage between the DC input terminals.” The term
“voltage source” implies that voltage is provided, but the
claim only sets out an indication of what the element
“does, not what it is structurally.” Laitram, 939 F.2d at
1536. The recited function implies no more structure
than the term “voltage source” itself. While “DC input
terminals” is a structural term, the input terminals
receive rather than provide DC voltage. Thus, the claim
does not contain structural language that is sufficient to
remove “voltage source means” from the reach of § 112, ¶
6.
    In some circumstances, expert testimony may be pro-
bative of whether a claim term itself corresponds to
sufficiently definite structure. In Rembrandt Data Techs.,
LP v. AOL, for example, we relied on expert testimony to
confirm that the terms “fractional rate encoding” and
“trellis rate encoding” were commonly used in publica-
tions to identify defined algorithms (i.e., structure) known
in the art. 641 F.3d 1331, 1340–41 (Fed. Cir. 2001).
Because the terms were “self-descriptive,” we held that
the terms “fractional rate encoding means” and “trellis
encoding means” were not governed by § 112, ¶ 6, not-
withstanding the word “means.” Id. at 1340–41.
    Lighting Ballast relies on expert testimony to support
its argument that “voltage source means” implies struc-
ture and, as a result, means-plus-function claiming does
not apply. Dr. Roberts, Lighting Ballast’s expert, testified
10                    LIGHTING BALLAST   v. PHILIPS ELECTRON
that “[t]he ‘voltage source’ limitation connotes, or sug-
gests, to me, and would connote to anyone skilled in the
art, the structure of a rectifier. . .” because “the only way
for a [l]ighting [b]allast to convert AC (from a ‘power line
source’ such as a wall outlet or other similar AC power
source in a home or office) into DC (for use at the ‘DC
supply voltage’) is through a rectifier.” Joint App. 21. Dr.
Roberts also stated that a battery could be used as the
“voltage source means” if a DC power source was used.
Id. at 21–22.
    Lighting Ballast’s expert testimony suggests that
some structure for performing the recited function is
implied, but it does not cure the absence of structural
language in the claim itself. Nor does the testimony
establish that the term “voltage source” was used syn-
onymously with a defined class of structures at the time
the invention was made, unlike the testimony in Rem-
brandt. See id. at 1341. In fact, Lighting Ballast’s record
testimony suggests a lack of a defined class of structures.
While a rectifier and a battery may be examples of struc-
tures that commonly perform the recited function, there
are many other ways to provide DC voltage, including
“generators” and “solar voltaic cells,” as Lighting Ballast’s
expert admitted. Joint App. 1623.
    Lighting Ballast points to case law in which this
Court declined to apply means-plus-function claiming in
view of expert testimony and other extrinsic evidence
showing that certain claimed elements implied sufficient
structure. In those cases, however, we started from the
presumption that means-plus-function claiming did not
apply because the claim limitations at issue did not
include the word “means.” See MIT v. Abacus Software,
462 F.3d 1344, 1353 (Fed. Cir. 2006) (“The phrase ‘color-
ant selection mechanism’ is presumptively not subject to
112 ¶ 6 because it does not contain the term ‘means.’”);
Lighting World, Inc. v. Birchwood Lighting, Inc., 382 F.3d
1354, 1359 (Fed. Cir. 2004) (“Because the ‘connector
 LIGHTING BALLAST   v. PHILIPS ELECTRON                 11
assembly’ limitation does not contain the term ‘means,’ we
begin with the presumption that section 112 ¶ 6 does not
apply to that limitation.”); Apex Inc. v. Raritan Computer,
Inc., 325 F.3d 1364, 1372 (Fed. Cir. 2003) (“As an initial
matter, none of the claim limitations asserted by Raritan
to be means-plus-function limitations contains the term
‘means,’ which, as noted, is central to the analysis.”);
Greenberg v. Ethicon Endo-Surgery, Inc., 91 F.3d 1580,
1583 (Fed. Cir. 1996) (construing the term “detent
mechanism”; “means” did not appear in the claim.). In
this case, we start with the presumption that means-plus-
function claiming does apply because the claim limitation
includes the word “means.” ULT failed to present suffi-
cient evidence to overcome that presumption.
                     V. INDEFINITENESS
    Once a court determines that a claim limitation in-
voked means-plus-function claiming under § 112, ¶ 6,
construction of the limitation involves two steps. First,
the court must identify the claimed function. Applied
Med. Res. Corp. v. U.S. Surgical Corp., 448 F.3d 1324,
1332 (Fed. Cir. 2006). Second, the court must identify the
structure described in the specification that performs the
claimed function. Id. Here, the parties do not dispute the
district court’s construction of the claimed function. The
sole issue on appeal is whether the specification identifies
sufficient structure to support the claimed function. We
review a district court’s identification of the structure
corresponding to a means-plus-function limitation without
deference. JVW Enters., Inc. v. Interact Accessories, Inc.,
424 F.3d 1324, 1329 (Fed. Cir. 2005).
    A patentee may use a generic “means” expression to
describe a claim element, but “the applicant must indicate
in the specification what structure constitutes the
means.” Biomedino, 490 F.3d at 948. A patent must
point out and distinctly claim the invention. In re
Donaldson Co., 16 F.3d 1189, 1195 (Fed. Cir. 1994) (en
12                      LIGHTING BALLAST    v. PHILIPS ELECTRON
banc). Failure to disclose adequate structure to support a
generic “means” expression amounts to impermissible
functional claiming. Med. Instrumentation & Diagnostics
Corp. v. Elekta AB, 344 F.3d 1205, 1211 (Fed. Cir. 2003).
If the patentee fails to disclose adequate structure, the
claim is invalid as indefinite under 35 U.S.C. § 112, ¶ 2.
See In re Donaldson, 16 F.3d at 1195.
     We hold that the ’529 Patent fails to disclose structure
capable of “providing a constant or variable magnitude
DC voltage between the DC input terminals.” The specifi-
cation does not refer to a rectifier or any other structure
capable of converting AC supply voltage into useable DC
voltage. Nor does the specification disclose structure
capable of supplying useable DC voltage directly from a
DC supply voltage. Rather, the ’529 Patent mentions
drawing power from a power line source and DC supply
voltages without specifying a capable structure or class of
structures. See, e.g., ’529 Patent col. 1 l. 56, col. 2 l. 8, col.
3 ll. 6–7.
    As already noted, Lighting Ballast relies on expert
testimony to support its contention that one skilled in the
art would readily ascertain structures capable of perform-
ing the recited function. But “testimony of one of ordinary
skill in the art cannot supplant the total absence of struc-
ture from the specification.” Default Proof Credit Card
Sys., Inc. v. Home Depot U.S.A., Inc., 412 F.3d 1291, 1302
(Fed. Cir. 2005). Lighting Ballast’s testimony merely
demonstrates that several different structures could
perform the recited function, namely, a rectifier, battery,
solar cell, or generator. The possibility that an ordinarily
skilled artisan could find a structure that would work
does not satisfy the disclosure requirements of means-
plus-function claiming under § 112. Ergo Licensing, LLC
v. CareFusion 303, Inc., 673 F.3d 1361, 1363–64 (Fed. Cir.
2012); see also Blackboard, Inc. v. Desire2Learn Inc., 574
F.3d 1371, 1385 (Fed. Cir. 2009) (“That ordinary skilled
artisans could carry out the recited function in a variety
 LIGHTING BALLAST   v. PHILIPS ELECTRON                 13
of ways is precisely why claims written in ‘mean-plus-
function’ form must disclose the particular structure that
is used to perform the recited function.”).
    Because we hold that the term “voltage source means”
in claim 1 of the ’529 Patent invokes means-plus-function
claiming under § 112, ¶ 6, and because we find in the
specification no corresponding structure, we find the
asserted claims invalid for indefiniteness under § 112, ¶ 2.
We need not address the other issues raised by ULT. The
judgment below is
                       REVERSED
                           COSTS
   Each party shall bear its own costs.
