Patent ID: 8149031

Claim:
A duty-cycle feedback charge pump comprising: a reference charge pump having an interface to accept an input signal, an interface to accept a duty-cycle feedback signal, and an interface to supply an output signal; a replica charge pump having an interface to accept the input signal and an interface to supply the duty-cycle feedback signal; wherein the reference charge pump includes: a first p-channel metal-oxide semiconductor (PMOS) with a source connected to a first dc voltage and a gate connected to accept the input signal; a second PMOS with a source connected to a drain of the first PMOS, a gate connected to accept the duty-cycle feedback signal, and a drain connected to supply the output signal; a first n-channel MOS (NMOS) having a drain connected to supply the output signal and a gate connected to a second dc voltage, having a potential less than the first dc voltage; a second NMOS having a drain connected to a source of the first NMOS, a gate accepting the input signal, and a source connected to a third dc voltage, having a potential less than or equal to the second dc voltage; a first capacitor having a first terminal connected to the output signal and a second terminal connected to a dc voltage; wherein the replica charge pump includes: an inverter having an input to accept the input signal, and an output to supply the inverted input signal; a third PMOS with a source connected to the first dc voltage and a gate connected to accept the inverted input signal; a fourth PMOS with a source connected to a drain of the third PMOS, and a gate and a drain connected to the duty-cycle feedback signal; a third NMOS having a drain connected to supply the duty-cycle feedback signal and a gate connected to the second dc voltage; a fourth NMOS having a drain connected to a source of the third NMOS, a gate connected to accept the inverted input signal, and a source connected to the third dc voltage; and, a second capacitor having a first terminal connected to the duty-cycle feedback signal and a second terminal connected to a dc voltage.