A low noise charge pump for use in a PLL-based frequency synthesizer. The charge pump includes a timing controller and a plurality of charge-pump circuits. The timing controller receives a reference signal to generate a plurality of enable signals having non-overlapping phases, where the frequency of each enable signal is equal to that of the reference signal divided by the number of the enable signals. The charge-pump circuits are coupled in parallel and operate in a time-interleaved manner according to the enable signals. In response to a first and second control signal, the charge-pump circuits are able to generate respective output currents which are multiplexed together to form a charge-pump current.