| 摘要 |
A charge pump (CP) is proposed for supplying at its output (23) a first current in response to an up-pulse and sinking a second current in response to a down-pulse, which charge pump comprises first means (200, 22, CM1) for converting the first control signal into the first current and second means (206, 208, CM2) for converting the second control signal into the second current, said first and second means comprising means (CM1, CM2) for filtering the respective control signals. It is recognized that a charge pump does not have to supply or sink current pulses which are rectangularly shaped in order for it to properly carry out its function. In the invention, the current sources supply or sink current pulses are smoothly shaped because the control signals supplied to the current sources are filtered. This causes the demands on the high frequency performance of the current sources to be greatly reduced. Consequently, relatively slow current sources may be used without the performance of the charge pump being limited by these slow current sources. |
