Ring VCO를 사용한 UHF 대역 CMOS Fractional-N 주파수합성기 설계

In this paper, we describe a UHF-band CMOS fractional-N frequency synthesizer using a ring - type VCO. It has been designed using 0.18㎛ CMOS technology. First, The newly designed charge-pump circuit includes an OTA for matching between the upper current and the lower current. In addition, a ring - type VCO is also used for small chip size. The simulation results show that the designed circuit has a phase noise of -109.53㏈c/㎐ at 1㎒ offset and consumes 19.4㎃ from a 1.8V supply. The lock time is less than 30usec and the chip size is 0.45㎜×0.5㎜.