Mixed snubber capacitance for paralleled semiconductors to reduce electro-magnetic interference

A Dual Active Bridge DC-DC converter comprising:

• a high voltage power stage;
• a low voltage power stage;
• a transformer coupling the high voltage power stage to the low voltage power stage,
• the high voltage power stage including first circuitry configured to
• during operation in a down-conversion mode,
• generate a high voltage, time varying output signal based on a high voltage DC input signal,
• transmit the high voltage, time varying output signal to the transformer;
• and
• during operation in an up-conversion mode,
• receive a high voltage, time varying input signal from the transformer, and
• generate a high voltage DC output signal based on the high voltage, time varying input signal;
• the low voltage power stage including second circuitry configured to
• during operation in the up-conversion mode,
• generate a low voltage, time varying output signal based on a low voltage DC input signal, and
• transmit the low voltage, time varying output signal to the transformer, and
• during operation in the down-conversion mode,
• receive a low voltage, time varying input signal from the transformer, and
• generate a low voltage DC output signal based on the low voltage, time varying input signal;
• and
• the second circuitry including,
• a plurality of switching transistors coupled in parallel with each other, and
• a plurality of snubber capacitors coupled in parallel to different switching transistors of the plurality of switching transistors, the plurality of snubber capacitors having mixed capacitance values.

A method of converting a first DC voltage to a second DC voltage, the method comprising:

• converting the first DC voltage to a first time varying voltage using first switching transistors;
• transforming the first time varying voltage to a second time varying voltage, different from
• the first time varying voltage, using a transformer;
• converting the second time varying voltage to the second DC voltage using second switching transistors, the second DC voltage being different from the first DC voltage;
• and
• at least one of converting the first DC voltage to the first time varying voltage, or converting the second time varying voltage to the second DC voltage, include spreading noise signals generated by corresponding switching transistors over a plurality of different frequencies.