PLL arrangement, charge pump, method and mobile transceiver

摘要

A charge pump arrangement for a phase-locked-loop has a current source circuit (60) which provides charging current to the phase locked loop, and a current sink circuit (90) which depletes charging current from the phase locked loop. The current source circuit (60) and the current sink circuit (90) have slew rates which have a predetermined relationship. In this way, the charge pump causes substantially no non-linear charge injection in the phase-locked-loop. Cascoded current mirrors (75, 85) are utilised to provide a high voltage with thin gate oxide technology. The arrangement has a relatively small die size. Since bias currents of the arrangement are mirrored according to the output current required, improved transient times are produced, leading to reduced phase noise.