Low phase noise CMOS VCO for UHF RFID reader system

This paper presents an optimized LC-VCO using an NMOS transistor, having low parasitic components and a customized inductor with a high quality factor, for UHF RFID reader systems. For the UHF RFID reader system-on-chips, a VCO with a wide frequency tuning range of more than 120MHz and low phase noise characteristics is required. Based on the low-cost CMOS process, the optimized NMOS VCO was designed and implemented. From the experimental results, the optimized LC-VCO exhibited a wide-tuning range of 415MHz, from 1.508 to 1.923GHz, and a low phase noise of -120.78dBc/Hz at a frequency offset of 200KHz. An FOM of -184.1 was achieved.