“Google argued that the PTAB abused its discretion by not considering its obviousness argument [but] the PTAB refused to consider [the] argument, explaining that it was impermissibly raised for the first time in Google’s reply brief, preventing Koninklijke Philips from being able to respond.”

On October 23, the U.S. Court of Appeals for the Federal Circuit (CAFC) affirmed a decision of the Patent Trial and Appeal Board (PTAB) that Google failed to meet its burden of establishing that Koninklijke Philips’ (Philips’) patent claims at issue were unpatentable on either of two grounds: 1) anticipation by Patent Cooperation Treaty (PCT) International Application Publication No. 98/52187 (the Tucker invention), or 2) obviousness over Tucker in view of the prior art (nonprecedential).

Google PTAB Proceedings

In 2016, Google petitioned the Patent Trial and Appeal Board (PTAB) of the United States Patent and Trademark Office (USPTO) for inter partes review (IPR) of Claims 10-16 and 20-21 of U.S. Patent No. 6,772,114 (the ’114 patent) owned by Philips, entitled “High Frequency and Low Frequency Audio Signal Encoding and Decoding System.” In 2018, the PTAB issued a final written decision holding that Google had not shown by a preponderance of the evidence that claims 10-16, 20, and 21 of the ‘114 patent were unpatentable.

The ‘114 patent relates to an encoding scheme for transmitting audio signals. According to the ‘114 patent, prior transmission systems that split a signal into spectral portions required considerable computation capacity. The transmission system described in the ’114 patent purports to improve upon those prior systems by reducing computation capacity. Specifically, the ‘114 patent describes a transmitter that uses Linear Predictive Coding (LPC) to code the high frequency portion of a signal prior to transmission. LPC coding reduces the computation capacity of a coding device in the transmitter because LPC coding does not require a down-sampler. Additionally, the ’114 patent describes a receiver that uses white noise as a source to reconstruct the high frequency portion of a received signal. This reduces the computation capacity of the receiver.

The challenged claims all require a “second decoder” that applies a high-pass filter to a noise signal, generating a reconstructed signal within a high-frequency range. This is illustrated in claim 10:

“10. A transmission system, comprising: a transmitter including a splitter for splitting up a transmission signal into a low frequency signal within a low frequency range and a high frequency signal within a high frequency range, the low frequency range being lower than the high frequency range, a first coder for deriving a first coded signal within the first frequency range from the low frequency signal, and a second coder for deriving a second coded signal within the high frequency range from the high frequency signal; a receiver in electrical communication with said transmitter to receive the first coded signal and the second coded signal, said receiver including a first decoder for sequentially applying a narrow-band decoder, an up-sampler and a low-pass filter to the first coded signal to generate a first reconstructed signal within the first frequency range, and a second decoder, wherein, based on the second coded signal, said second decoder sequentially applies a high-pass filter, a LPC synthesis filter and an amplifier to a noise signal to generate the second reconstructed signal.”

Burden Not Met Through Combining Art

The Federal Circuit’s opinion explained that it was undisputed that the claimed high-pass filter transmits frequencies above the cutoff frequency and substantially attenuates all others. However, Google argued that Tucker’s disclosure of a low-pass filter and reflection step when combined are prior art to the claimed high-pass filter, because the combination transmits the high-band portion of the input signal while attenuating the low-band portion of the input. The CAFC disagreed with this. The Tucker low-pass filter, argued the Board, transmits frequencies below the given cutoff frequency, and the reflection step only serves to take the low-frequency band output of the low-pass filter and move it to the high-frequency band. This shows that in the Tucker invention, the low-frequency content of the input signal is transmitted without any transmission of the input signal’s high frequency-content. Therefore, the CAFC held that the Tucker invention was not anticipated by the ‘114 patent because the invention did not transmit the high-frequency content of an input signal; thus, it could not disclose the high-pass filter.

Additionally, Google argued that the Tucker invention’s low-pass and reflection steps disclosed the high-pass filter because its result was the same as a high-pass filter. The CAFC also disagreed with this, holding that the similarities between the two inventions did not transform the Tucker low-pass filter and reflection steps into a high-pass filter that transmits high-band content. The court went on to explain that even where the design of a high-pass filter may include a low-pass filter, this inclusion does not necessarily change the function of the high-pass filter. For instance, in the ‘114 patent, the low-pass filter may be used to attenuate the portion of the input signal below the cut-off frequency, allowing only those frequencies above the cut-off to be transmitted by the high-pass filter. In contrast, the Tucker invention only transmits the portion of an input signal that is below the cut-off frequency. Thus, the court held that Google failed to meet its burden to establish that the challenged claims were anticipated, because the Tucker invention and the ‘114 patent were separate and distinct.

Final Plea to the CAFC

Lastly, Google argued that the PTAB abused its discretion by not considering its obviousness argument. Google argued in its IPR petition that the claims at issue were obvious over Tucker, because it would have been obvious to include a high-pass filter in Tucker’s receiver in place of the low-pass filter and reflection process. The PTAB refused to consider this argument, explaining that it was impermissibly raised for the first time in Google’s reply brief, preventing Philips from being able to respond. The CAFC held that the PTAB was within its discretion in declining to consider the argument, as the argument was outside of the scope of the IPR petition. The CAFC therefore affirmed the PTAB’s conclusion that Google failed to meet its burden of showing that the challenged claims were obvious or anticipated by Tucker or other prior art.