A switching regulated power supply, the output voltage of which is regulated according to a pulse width modulation method, is provided with a reference oscillator for generating first and second synchronizing signals, phases of which are complement each other, first and second time constant circuits,...http://www.google.ca/patents/US5140513?utm_source=gb-gplus-sharePatent US5140513 - Switching regulated DC-DC converter using variable capacity diodes in the feedback circuit
