Differential charge pump using surtchingly controlled current generators

摘要

A differential charge pump circuit employing a lowpass filter network which is chargeable and dischargeable by switchingly controlled current generators. The differential charge pump employs two identical current generators for injecting the same current I in a substantially continuous manner, on the two significant nodes of the lowpass filter. The differential charge pump also employs two pairs of identical, switchingly controlled current generators connected to the two significant nodes, respectively, each capable of pulling a current I. The two generators forming each of the two pairs of switchingly controlled current generators are controlled by one of a pair of control signals (UP, DOWN) and by the inverted signal of the other of the pair of control signals, respectively. All four switchingly controlled generators may be of the same type (N-type), thus ensuring high speed and precision. The two identical (P-type) current generators employed for continuously injecting the same current I on the two nodes of the lowpass filter may be controlled through a common mode feedback loop for enhanced precision.