IP Law Daily, PATENT—Fed. Cir.: PTAB’s obviousness ruling for flash memory patent upheld, (Jan 8, 2026)

By Carolin Dennis, B.Sc., LL.B., LL.M.

The PTAB properly determined that all the challenged claims of Viasat Inc.’s data error correction patent were unpatentable for obviousness relying on prior art published patent applications.

In a nonprecedential disposition, the U.S. Court of Appeals for the Federal Circuit affirmed the Patent Trial and Appeal Board’s (PTAB) decision that certain claims of Viasat, Inc.’s patent directed to error correction in flash memory data were unpatentable for obviousness because substantial evidence supported the PTAB’s decision. The Federal Circuit relied on Linear Technology Corp. v. International Trade Commission and applied the same analysis in this case (Viasat, Inc. v. Western Digital Technologies, Inc., No. 2024-1483 (Fed. Cir. Jan. 7, 2026)).

Background. Viasat, Inc. (Viasat) is the owner of U.S. Patent No. 8,966,347 (the ’347 patent), titled “Forward Error Correction with Parallel Error Detection for Flash Memories.” The patent is directed to methods and systems for error correction in data retrieved from flash memory. Western Digital Technologies, Inc. (Western Digital) filed a petition for inter partes review of claims 1 through 11 and 13 through 23 of the ’347 patent. The PTAB concluded that Western Digital had shown that claim 13 of the ’347 patent was unpatentable for obviousness. Based on that conclusion and its analysis of the other claims before it, the PTAB found that claims 1 through 11 and claims 13 through 23 would have been obvious in light of the combination of Diggs and Cheng. Thus, the PTAB granted the petition, and determined that all the challenged claims were unpatentable for obviousness relying on prior art published patent applications to Diggs (Pub. No. US 2009/0070651) and Cheng (Pub. No. US 2009/0276570). Viasat appealed to the Federal Circuit focusing entirely on the PTAB’s analysis of the patentability of claim 13.

Claim 13. Viasat argued that claim 13 of the ’347 patent requires that the “decoder” both “retrieve the encoded data” and “correct errors.” According to Viasat, the difference between Diggs and the invention recited in claim 13 of the ’347 patent is that in Diggs the ECC Detection and Correction structure performs one of the functions of the decoder of claim 13 (processing the data stream to correct errors in the data stream) but does not perform the other designated function of the decoder (retrieving data from the flash memory to generate a data stream).

Viasat argued that in Diggs that function is performed not by the decoder (the ECC Detection and Correction module), but by the Controller. Viasat argued that the controller of claim 13 does not retrieve the data stream from the flash memory, but simply monitors the error rate and activates the additional error correction feature if and when needed. According to Viasat, the difference in the respective roles of those two components in Diggs and in the device recited in claim 13 constitutes a fundamental structural distinction between the architecture of Diggs and the architecture of claim 13. In view of that difference, Viasat argued that the PTAB erred in finding that the limitations in claim elements 13[c] and [d] were disclosed by Diggs.

The Federal Circuit noted that Figure 1 of Diggs showed that the ECC Detection and Correction module (125) in Diggs is part of the Controller (114), and the text of the Diggs reference confirmed that the “controller 114 further includes an ECC detection and correction module 125.” The two functions that the ’347 patent assigns to the decoder are thus performed by the Controller in Diggs through the incorporated ECC Detection and Correction module. The PTAB therefore properly rejected Viasat’s core argument for distinguishing Diggs—that a single entity in Diggs does not perform both the retrieval function and the processing function. Accordingly, the Federal Circuit did not find Viasat’s argument persuasive and noted that it would reach the same result in this case if we viewed the PTAB as having based its decision on an implicit construction of claim 13 as not requiring that the decoder and controller consist of physically separate circuitry.

Viasat also cited two cases Becton, Dickinson & Co. v. Tyco Healthcare Group, 616 F.3d 1249 (Fed. Cir. 2010) and Kyocera Senco Industrial Tools Inc. v. International Trade Commission, 22 F.4th 1369 (Fed. Cir. 2022), involving mechanical patents in which the claims recited inventions having distinct components. In Becton, the court held that when a claim lists elements separately, “the clear implication of the claim language is that those elements are distinct components of the patented invention.” In Kyocera, the court similarly explained that when a patent claim separately lists two mechanical components, it is presumed that those components are distinct. However, the Federal Circuit found that those cases dealt with mechanical patents and that they were less clearly applicable to electronic patents in which particular functions are frequently performed by combinations of circuitry that are not necessarily contained in segregated physical packages.

The Federal Circuit cited Linear Technology Corp. v. International Trade Commission, 566 F.3d 1049 (Fed. Cir. 2009) which involved claims of an electronic patent that recited a “second circuit” and a “third circuit” that performed particular functions circuits in which the International Trade Commission (ITC) and the Federal Circuit construed the two terms “to not require entirely separate and distinct circuits.”

The Federal Circuit noted that the same analysis applies in this case. While there is overlap in the Diggs circuitry that performs the functions of the controller and the decoder of the ’347 patent, nothing in the ’347 patent suggests that such overlap is impermissible. The Federal Circuit found that the specification of the ’347 patent makes it clear that the components of the systems claimed in the patent—particularly the encoder, the decoder, and the controller may be implemented by various circuits that individually or collectively are adapted to perform some or all of the applicable functions in hard-ware. The specification of the ’347 patent thus makes it clear that under the proper construction of claim 13, the identity of the particular module or sub-module that performs each task is not critical.

Thus, the Federal Circuit agreed with the PTAB that the Diggs reference maps to the structures and functions set forth in claim elements 13[c] and [d] of the ’347 patent. Accordingly, the PTAB’s decision that the combination of Diggs and Cheng rendered claim 13 unpatentable for obviousness was affirmed.

The Case is No. 24-1483.

Judge: Bryson, W.

Attorneys: Matthew R. Ford (Bartlit Beck LLP) for Viasat, Inc. Brian M. Buroker (Gibson Dunn & Crutcher, LLP) for Western Digital Technologies, Inc.

Companies: Viasat, Inc.; Western Digital Technologies, Inc.

Cases: Patent FedCirNews USPTO