摘要：A fully-differential charge pump（FDCP）with perfect current matching and low output current noise is realized for phase-locked loops（PLLs）.An easily stable common-mode feedback（CMFB）circuit which can handle high input voltage swing is *** mismatch and current noise contribution from the CMFB circuit is *** order to optimize PLL phase noise,the output current noise of the FDCP is analyzed in detail and calculated with the sampling *** calculation result agrees well with the *** on the noise analysis,many methods to lower output current noise of the FDCP are *** fully-differential charge pump is integrated into a 1–2 GHz frequency synthesizer and fabricated in an SMIC CMOS 0.18μm *** measured output reference spur is–64 dBc to–69 *** in-band and out-band phase noise is–95 dBc/Hz at 3 kHz frequency offset and–123 dBc/Hz at 1 MHz frequency offset respectively.