Duty cycle corrector systematic offset reduction

A method for operating a charge pump, the charge pump including a first transistor providing a first current, a second transistor providing a second current, a first switch coupled between the first transistor and an output of the charge pump, a second switch coupled between the output of the charge pump and the second transistor, a third transistor, a fourth transistor, and a bias circuit biasing a gate of the second transistor and a gate of the fourth transistor, wherein a gate of the third transistor is coupled to a gate of the first transistor, and a drain of the third transistor is coupled to a drain of the fourth transistor, the method comprising:

• sensing a first voltage at the output of the charge pump;
• sensing a second voltage at the drain of the third transistor;
• driving the gate of the third transistor in a direction that reduces a difference between the second voltage and the first voltage;
• receiving a clock signal;
• and
• driving the first switch and the second switch based on the clock signal.