| 摘要 |
The charge pump, having increased precision over known charge pumps, for a self-biasing phase-locked loop and a self-biasing delay-locked loop is disclosed herein. It includes a p-type charge pump and a n-type charge pump. The charge pump has inputs for an up and a down voltage output from a phase and frequency detector and for at least two bias voltage outputs from a bias generator. The p-type charge pump is coupled to the up output of the phase and frequency detector and a first bias voltage output from the bias generator circuit. The n-type charge pump is coupled to the p-type charge pump and has inputs coupled to the down output of the phase and frequency detector and a second bias voltage output from the bias generator circuit. A first capacitor is coupled across the p-type charge pump. This charge pump operates between 1 muA to 10 muA. It is a more balanced design than known charge pump designs. Although PMOS is very slow, the present implementation of both the p-type and the n-type charge pumps pull up and pull down at the same time. This charge pump can be used with very narrow bandwidths. As another advantage, due to the up voltage output of the phase and frequency detector increasing at a rate approximate to current down voltage output, a relatively small amount of phase noise exists. With reference to phase error correction, this charge pump implementation more finely tunes the output signal of the phase locked loop design.
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