PTAB

IPR2022-00320

Power Integrations Inc v. Opticurrent LLC

Key Events

Petition

petition

Title: Three Terminal Noninverting Transistor Switch
Brief Description: The ’623 patent discloses a self-powered, three-terminal noninverting transistor switch. The technology is presented as an improvement over prior art by replacing bipolar transistors with metal-oxide-semiconductor (MOS) transistors to reduce current consumption, with the switch deriving its operating power from the voltage across its output terminals.

Prior Art Relied Upon: Faini (Patent 4,720,641).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Faini, which discloses a self-powered switching device, teaches every element of claims 1-4. Faini’s MOS power element 1 (the output transistor) and its CMOS pilot circuit 6 (the inverter) provide two stages of inversion, resulting in a noninverting switch. Faini’s circuit is self-powered via an internal voltage stabilizer (control logic circuit 9 and charge circuit 12) that draws power from across the output terminals to charge a condenser 11. Petitioner asserted that the connection to this off-chip condenser does not constitute a "fourth terminal connected to a power supply" under the district court’s construction of the claim preamble, as the power is derived internally rather than from an external source. The main transistor is an N-channel, enhancement-mode MOSFET as required by dependent claims 3 and 4.
- Key Aspects: This ground heavily relies on a district court claim construction from prior litigation that allows a "three terminal" switch to have more than three physical pins, provided an extra pin is not for an external power supply.

Prior Art Relied Upon: Faini (Patent 4,720,641).
Core Argument for this Ground:
- Prior Art Mapping: This ground was presented as an alternative, arguing that even if the Board were to construe the preamble as strictly requiring only three terminals, Faini would still render the claims obvious. Faini discloses its core switching function along with additional "input terminals 10" for "auxiliary functions."
- Motivation to Modify: Petitioner contended that a person of ordinary skill in the art (POSITA) would have recognized that the auxiliary functions enabled by the extra input terminals were not required for the core operation of Faini's self-powered switch. A POSITA would combine this knowledge with Faini's stated goals of achieving "cost and simplicity" to implement the device using only a single input terminal, thereby creating a switch with only three terminals.
- Expectation of Success: The modification was a simple omission of superfluous components to achieve a known goal (cost reduction) and would have yielded the predictable result of a functional, three-terminal self-powered switch.

Prior Art Relied Upon: Maeda (Patent 5,952,740) and Ong (Dewitt G. Ong, Modern MOS Technology, 1984).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner asserted that Maeda discloses a self-powered, noninverting transistor switch with all the core components of claim 1: a main transistor (FET Sw1), a voltage stabilizer that derives power from across the transistor's terminals, and an inverter circuit (Q1) that drives the transistor.
- Motivation to Combine: The Ong textbook teaches the known advantages of using a complementary MOS (CMOS) inverter, including higher speed, wide output voltage swing, and low static power dissipation. Petitioner argued a POSITA would be motivated to implement Maeda’s generic inverter Q1 as a CMOS-type inverter as taught by Ong. This modification would directly further Maeda’s stated goal of keeping the inverter's power source voltage "fixed over a longer time," as the low power consumption of a CMOS inverter would reduce the drain on Maeda’s internal power storage capacitors.
- Expectation of Success: A POSITA would have had a reasonable expectation of success in this combination, as it involved applying a well-known, superior component (a CMOS inverter) to a known circuit (Maeda's switch) to achieve the predictable benefits of improved performance and efficiency.

"a noninverting transistor switch having only three terminals": Petitioner adopted the prior district court construction, which defines this term as "a noninverting transistor switch with three terminals that does not have a fourth terminal connected to a power supply." This construction is critical to the anticipation argument, as it allows Faini's four-pin embodiment (with the fourth pin connected to an internal filtering capacitor) to meet the "three terminal" limitation.
"CMOS inverter interrupting the passing of current": Petitioner proposed construing this to require the inverter to interrupt only the current path through the inverter itself, not all possible current paths between the voltage stabilizer and the second terminal. This position was based on the patent owner's successful infringement arguments in prior litigation.

Petitioner argued that discretionary denial under Fintiv was inappropriate. The parallel district court litigation was in its very early stages, with no trial date set, making it likely the IPR would conclude first.
Petitioner further argued that the prior art and invalidity grounds presented in the petition (Faini and Maeda/Ong) were not raised during the original examination, a subsequent reexamination, or in the parallel litigation, meaning there was no risk of duplicative efforts or inconsistent results.
Regarding §325(d), Petitioner asserted that Faini and Maeda are not cumulative of art previously considered by the USPTO. It was also noted that the Patent Owner was aware of Faini and Maeda from a corresponding European prosecution but failed to disclose them during the U.S. reexamination.

Petitioner requested the institution of an inter partes review and the cancellation of claims 1-4 of the ’623 patent as unpatentable.