PTAB

IPR2021-00073

Fantasia Trading LLC v. CogniPower LLC

Key Events

Petition

petition

Title: POWER CONVERTER WITH DEMAND PULSE ISOLATION
Brief Description: The ’713 patent discloses a switched-mode power converter with galvanically isolated primary and secondary control circuits. The secondary circuit regulates the output voltage by sending "demand pulses" across an isolation barrier to control the turn-on of a primary-side power switch, while the turn-off is controlled by the primary circuit. A key disclosed feature is a secondary-side bias circuit that uses a rectifier poled to charge a capacitor during "forward pulses" of the converter.

Prior Art Relied Upon: Matsumoto (Patent 7,773,392) and Mao (Patent 6,466,461).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Matsumoto disclosed nearly all elements of the challenged claims, including a two-controller, isolated power converter where a secondary circuit sends "turn on" demand pulses to a primary circuit that controls turn-off. Petitioner contended the only key element missing from Matsumoto was the specific secondary-side bias circuit recited in the claims. Mao was argued to disclose this missing element: a forward-based bias circuit that powers secondary-side electronics using a rectifier poled to charge a capacitor during the forward phase (when the primary switch is on), which Petitioner asserted was a well-known technique.
- Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Matsumoto’s converter with Mao’s bias circuit to improve performance. Conventional bias circuits powered from the converter’s output voltage are vulnerable to fluctuations, especially in low-voltage or constant-current applications. Mao’s circuit solved this known problem by providing a stable bias voltage independent of the output, making the converter more robust and broadly applicable.
- Expectation of Success: The combination involved applying a known solution (Mao's bias circuit) to a known problem in a predictable manner, ensuring a high expectation of success.

Prior Art Relied Upon: Matsumoto (Patent 7,773,392), Mao (Patent 6,466,461), and Krupka (Patent 4,413,224).
Core Argument for this Ground:
- Prior Art Mapping: This ground builds on the Matsumoto and Mao combination by adding Krupka to teach the limitations of claim 53, specifically a demand pulse generator comprising a gated oscillator. Petitioner asserted that while Matsumoto’s generator creates a one-shot pulse, Krupka taught a hysteretic controller using an oscillator and logic circuitry (an AND-gate) to selectively gate pulses when the output voltage falls below a reference. This structure provides a stream of demand pulses to quickly correct the output voltage.
- Motivation to Combine: A POSITA would have recognized the circuits in Matsumoto and Krupka as known alternatives for generating switching signals. A POSITA would combine Krupka's gated-oscillator technique with Matsumoto’s converter to improve the generation of demand pulses and reduce output voltage ripple, a known benefit of hysteretic control. This was presented as a simple substitution of one known functional block for another to gain a predictable advantage.
- Expectation of Success: Applying Krupka's well-understood gated-oscillator control method to Matsumoto's converter was argued to be a straightforward modification that would predictably improve performance.

Prior Art Relied Upon: The combination for Ground 2, plus Tisinger (Patent 5,418,410).
Core Argument for this Ground:
- Prior Art Mapping: This ground adds Tisinger to the combination of Matsumoto, Mao, and Krupka to teach the limitation of claim 57: a circuit configured to avoid premature turn-off of the primary switch due to capacitive charging. Tisinger disclosed a Leading Edge Blanking (LEB) circuit, which addresses the well-known problem of current spikes at switch turn-on that can falsely trigger over-current protection.
- Motivation to Combine: Petitioner contended that LEB circuits were ubiquitous and essential components in switched-mode power supply controllers. A POSITA implementing the Matsumoto converter would have inherently understood the need for a current-sense and LEB circuit to protect the power switch and ensure reliable operation. Adding Tisinger's conventional LEB circuit was a necessary and obvious design choice.

Prior Art Relied Upon: The combination for Ground 2, plus Szepesi (Patent 5,498,995).
Core Argument for this Ground:
- Prior Art Mapping: This ground adds Szepesi to teach the limitation of claim 59: using a primary-side bias winding to power the primary control circuit. Szepesi disclosed the conventional technique of using an auxiliary "bootstrap" winding on the main transformer to efficiently power the primary-side controller after startup, which is more efficient than powering it directly from a high-voltage input rail.
- Motivation to Combine: A POSITA would have recognized that Matsumoto's primary controller required a source of bias power to function. The method disclosed in Szepesi was a standard, well-known, and power-efficient way to provide this bias power in offline converters. Implementing this conventional technique in the Matsumoto design was presented as an obvious and routine step for any competent circuit designer.

Petitioner argued that discretionary denial under §314(a) based on Fintiv factors would be inappropriate. The petition asserted that the parallel district court litigation was in its very early stages, with a trial date set for well after the IPR Final Written Decision would be due. Petitioner further contended that its investment in the IPR was substantial and that it would stipulate not to pursue the same invalidity grounds in district court, thereby avoiding duplicative efforts and conserving judicial resources. Finally, Petitioner argued the merits of the petition were particularly strong, favoring institution for systemic efficiency and integrity.

Petitioner requested institution of an inter partes review and cancellation of claims 52-61 of the ’713 patent as unpatentable on all asserted grounds.