Patent ID: 6586980
Filing Date: 2003-07-01
Classification: G05F,G11B,H03K

Abstract:
An apparatus, comprising:a voltage ramp generator capable of discharging a capacitor comprising, a reference current coupled to a first supply voltage; a current mirror, coupled to a second supply voltage, comprising a reference transistor in the reference leg and a mirror transistor in the mirror leg, wherein the mirror transistor is controlled in part by the reference transistor; and a biasing arrangement coupled between the reference current and the current mirror and to an output voltage of the capacitor capable of being linearly discharged; wherein when the output voltage of the capacitor falls below a first interim voltage and the mirror transistor goes from a high resistance region of operation into a low resistance region of operation, the biasing arrangement operatively causes the reference transistor to likewise enter the low resistance region of operation while maintaining a predetermined current relationship between the reference transistor and the mirror transistor.