Patent ID: 6016259
Filing Date: 2000-01-18
Classification: H02M,Y02B

Abstract:
A power supply circuit, comprising:a voltage driven type switching element having a control terminal for repeatedly changing between an ON state and an OFF state;an LC resonant circuit connected to said switching element and has a predetermined resonant frequency;a delay resistor directly connected to said control terminal of said switching element;a feedback winding for applying a feedback voltage derived from a high frequency signal across said LC resonant circuit to said control terminal through said delay resistor, said feedback voltage being delayed by said delay resistor before being applied to said control terminal; anda bias circuit connected to said feedback winding for providing a bias voltage to said control terminal through said feedback winding and said resistor for alternately switching between said ON and Off states in combination with said feedback voltage;wherein said voltage driven type switching element has an input impedance sufficiently higher than a source impedance of said feedback voltage in such a way that substantially no current flows into said control terminal of said switching element by said feedback voltage, and wherein said feedback voltage is delayed by a time defined by said delay resistor and an input capacitor of said switching element before being applied to said control terminal.