| 摘要 |
A phase-switching dual modulus prescaler having a dual modulus divider is provided. Said divider comprises a first and second divide-by-2 circuit (A;B), wherein said second divide-by-2 circuit (B) is coupled to the output of said first divide-by-2 circuit (A) and at least said second divide-by-two circuit (B) comprises a four phase output each separated by 90°. A phase selection unit (PSU) is provided for selecting one of the four phase outputs (Ip, In, Qp, Qn; INi, INni, INq, Innq) of the second divide-by-2 circuit (B). Moreover, a phase control unit is provided for providing control signal (C1, NC0; C2, NC2; C3, NC3) to the phase selection unit, wherein the phase selection unit (PSU) performs the selection of the four phase outputs (Ip, In, Qp, Qn; INi, INni, INq, Innq) according to the control signals (C0, NC0; C1, NC1; C2, NC2). Said phase selection unit (PSU) is implemented based on direct logic. The implementation of the phase selection unit based on direct logic enables a higher speed and saves area on the chip.
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