Patent ID: 7400119

Claim:
A high voltage power supply comprising: DC-DC converter having a low voltage input to which an input current is applied and a high voltage output at which an output current and an output voltage are developed; a voltage controlled resistor being electrically coupled to said high voltage output in parallel with said DC-DC converter and having a control input wherein a resistance of said voltage controlled resistor is determined by an input voltage applied to said control input of said voltage controlled resistor; and a feedback circuit operatively connected between said high voltage output of said DC-DC converter and said control input of said voltage controlled resistor, said feedback circuit being responsive to each of a reference voltage and a feedback signal proportional to said output voltage and operative to develop said input voltage which varies as a function of variation in said feedback signal, said voltage controlled resistor in response to variation of said input voltage being operative to vary said resistance such that variation of said resistance is in opposition to a variation of said output voltage to maintain said output voltage substantially constant.