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Switch Realization for DC-DC Converters

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(1) diode off, v(t) negative, i(t) is zero

(2) i(t) increases to positive, charging the junction cap. , diode becomes forward biased.

(3) diode on(4) turn off diode,

but the diode remains on while minority charge present in p-n- junction.

(5) until all minority charges (Qr) emoved, then diode is off, i(t) =0

a peak value due to lightly doped n- region exhibits large resistance

tr reverse recovery time

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MOS from ON to OFF

Diode from OFF to ON

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Transistor from OFF to ON

Diode from ON to OFF

Switching loss

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Summary

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