A varactorless CMOS direct-injection locked frequency divider

作者：Jang S L^*; Liu C C

来源：Microwave and Optical Technology Letters, 2008, 50(3): 608-611.

DOI：10.1002/mop.23165

• varactor-less injection-locked frequency divider
• wide locking range
• quadrature generation
• CMOS

This paper presents a new integrated direct-injection locked frequency (ILFD) with the capability of quadrature generation. The circuit consists of a quadrature VCO, based on the cross-coupling of two differential LC-tank VCOs and with the coupling transistors placed in parallel with the switch transistors, and two direct injection MOSFETs. No varactors are used, and feedback is applied for frequency tuning. The circuit is implemented using a standard 0.35 mu m CMOS process. Measurement results show that at the supply voltage of 3.3 V, the core power consumption is 27 m W. The free-running ILFD is tunable from 1.5 to 1.98 GHz and the locking range is 2.92-4.26 GHz at 0 dBm. The measured phase noise of free-running ILFD is -118.3 dBc/Hz while the locked quadrature output phase noise is -126.7 dBc/Hz at 1 MHz offset frequency from the oscillation frequency of 1.98 GHz, which is 8.4 dB lower than the free running ILFD.

• 出版日期2008-3