Patent ID: 6717446
Filing Date: 2004-04-06
Classification: H03L

Abstract:
A programmable charge-pump circuit that provides an output signal to an output node in response to UP and DOWN signals, comprising:a charge-pump decoder circuit that is arranged to provide a first array of control signals in response to the UP signal and a program control signal, and also provide a second array of control signals in response to the DOWN signal and the program control signal, wherein the program control signal determines which of the first and second array of control signals are selected in response to the UP and DOWN signals, respectively, such that the non-selected control signals from the first and second arrays are maintained at a constant logic level; an array of selectable current sources, wherein each of the selectable current sources includes a current source circuit that is selectively series coupled to a corresponding cascode circuit when activated in response to a corresponding DOWN control signal from the first array of control signals, wherein each cascode circuit is biased to operate as a cascode for a respective one of the current source circuits such that each selected current source circuit provides a source current that flows from the current source circuit to the output node through the cascode circuit; and an array of selectable current sinks, wherein each of the selectable current sinks includes a current sink circuit that is selectively series coupled to another corresponding cascode circuit when activated in response to a corresponding UP control signal from the second array of control signals, wherein each other cascode circuit is biased to operate as a cascode for a respective one of the current sink circuits such that each selected current sink circuit provides a sinking current that flows from the output node to the current sink circuit through the other cascode circuit, whereby charge feed-through to the output node is minimized by maintaining constant logic levels on the control signals for the non-selected current source and sink circuits.