Conventional CMOS charge pump circuits have some current mismatching characteristics. The current mismatch of the charge pump in the PLLs generates a phase offset, which increases spurs in the PLL output signals. In particular, it reduces the locking range in wide range PLLs with a dual loop scheme. A new charge pump circuit with perfect current matching characteristics is proposed. By using an error amplifier and reference current sources, one can achieve a charge pump with good current matching characteristics. It shows nearly perfect current matching characteristics over the whole VCO input range, and the amount of the reference spur is >-75 dBc in the PLL output signal. The charge pump circuit is implemented in a 0.25 /spl mu/m CMOS process.
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机译：传统的CMOS电荷泵电路具有一些电流失配特性。 PLL中电荷泵的电流失配会产生相位偏移，这会增加PLL输出信号中的杂散。特别是，它通过双环路方案减小了宽范围PLL中的锁定范围。提出了一种具有理想电流匹配特性的新型电荷泵电路。通过使用误差放大器和参考电流源，可以实现具有良好电流匹配特性的电荷泵。它在整个VCO输入范围内显示出近乎完美的电流匹配特性，并且在PLL输出信号中基准杂散的数量> -75 dBc。电荷泵电路以0.25 / spl mu / m CMOS工艺实现。
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