A charge pump comprises a first current mirror that injects a first charging
current
onto a loop filter and a second charging current onto an integrator capacitor.
The first and second charging currents are controlled by a first common control
signal. The first charging current mirrors the second charging current. A second
current mirror drains a first discharging current from the loop filter and a second
discharging current from the integrator capacitor. The first and second discharging
is currents are controlled by a second common control signal. The first discharging
current mirrors the second discharging current. A sampling circuit couples the
second charging and discharging currents to the integrator capacitor, which charges
or discharges with a difference current between the second charging and discharging
currents. A control circuit detects a voltage difference between the loop filter
and integrator capacitor and adjusts the first common control signal to minimize
the voltage difference.
