Patent ID: 7130225

Claim:
A charge pump including a first current source and a second current source connected in series between a high voltage source and a low voltage source, the charge pump comprising: a PMOS transistor functioning as the first current source, a source of the PMOS transistor being connected to the high voltage source and a gate of the PMOS transistor being selectively connected to the high voltage source; a first capacitor connected to the high voltage source and selectively connected to a gate of the PMOS transistor; a first bias generator for charging the first capacitor; an NMOS transistor functioning as the second current source, a source of the NMOS transistor being connected to the low voltage source, and a drain of the NMOS transistor being connected to a drain of the PMOS transistor, and a gate of the NMOS transistor being selectively connected to the low voltage source; a second capacitor connected to the low voltage source and selectively connected to a gate of the NMOS transistor; and a second bias generator for charging the second capacitor, wherein the first and second bias generators include a current mirror circuit, wherein the current mirror circuit includes: a mirrored PMOS transistor having a source connected to the high voltage source and a gate connected to its drain and to the first capacitor; a first mirrored NMOS transistor having a source connected to the low voltage source and a gate connected to the second capacitor; a second mirrored NMOS transistor having a source connected to the low voltage source and a gate connected to the gate of the first mirrored NMOS transistor; and a bias current source connected between the high voltage source and a drain of the second mirrored NMOS transistor, wherein the gate and drain of the second mirrored NMOS transistor are connected, and wherein the drains of the mirrored PMOS transistor and the first mirrored NMOS transistor are connected.