EMI filter and frequency filters having capacitor with inductance cancellation loop

A filter circuit, comprising:

• a) a first capacitor;
• b) a second capacitor;
• c) a first inductor,
• wherein the first capacitor and second capacitor are connected to opposite ends of the first inductor;
• and
• d) a second inductor,
• wherein the first capacitor and second capacitor are connected to opposite ends of the second inductor,
• wherein the first inductor and second inductor are coupled,
• wherein the first inductor, second inductor, first capacitor and second capacitor are connected by circuit board traces, and
• wherein the first inductor and second inductor are disposed horizontally relative to a plane defined by the circuit board traces, and
• whereby the filter circuit filters signals which are applied across the first capacitor or applied across the second capacitor.

A filter circuit with reduced mutual inductance between capacitors, comprising:

• a) a first capacitor disposed on a circuit board;
• b) a second capacitor disposed on the circuit board;
• c) a first inductor, wherein the first capacitor and second capacitor are connected to opposite ends of the first inductor, wherein the first inductor is disposed horizontally relative to the circuit board;
• d) an inductance cancellation loop connected to the first capacitor or second capacitor, wherein the inductance cancellation loop is oriented such that it conducts current in a direction opposite the direction of current within the first capacitor or second capacitor,
• whereby the filter circuit filters signals which are applied across the first capacitor or applied across the second capacitor, and wherein the inductance cancellation loop is connected in series with the first capacitor or second capacitor in a high frequency model of the filter circuit.