Patent ID: 7479775
Filing Date: 2009-01-20
Classification: H02M

Abstract:
1. A negative voltage generator, comprising: a current mirror unit for receiving a first positive voltage from a first positive voltage source and a second positive voltage from a second positive voltage source and determining how to generate a first output current and a second output current according to a received positive reference voltage and the second positive voltage, wherein the values of the first output current and the second output current are proportional; a control unit for receiving the second output current and generating a control signal whose value depends on the voltage variation of a negative voltage generated by a negative voltage source; a first resistor connected between the second positive voltage source and a first output node; and a switching unit connected between the first output node and the negative voltage source, the on/off state of the switching unit being determined according to the control signal to keep the current passing through the switching unit constant and to generate a first output negative voltage having a constant level through the first output node.