A 5 GHz current controlled oscillator with active inductor

• Main Authors: Rajagopal, Chakaravarty D., Noh, Norlaili Mohd, Rajendran, Jagadheswaran, Ramiah, Harikrishnan
• Format: Article
• Published: Springer Science 2022
• Subjects: TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://eprints.um.edu.my/43273/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85125275473&doi=10.1007%2f978-981-16-8129-5_155&partnerID=40&md5=ec888bf3551a98685cbeb9069f6772d8

Oscillators play the key role in determining the quality of the RF communication systems. Most oscillators are voltage based (VCO) and are mainly in two types, which are the LC tank oscillators and the non-LC tank oscillators. The former is very good for lower phase noise due the usage of passive inductor. The latter, such as ring oscillators, are much smaller in size, thus lower cost, but exhibit much higher phase noise. However, current sources are becoming more popular and employed in oscillators to form Current Controlled Oscillator (CCO), as they produce higher frequency signals as compared to voltage source. Hence, the goal for this work was to design a CCO that produces 5 GHz center frequency, tuning range of 500 MHz and with phase noise better than −110 dBc/Hz by employing active inductor (AI-CCO). To demonstrate the proposed concept, a 5-stage ring oscillator with active inductor and controlled by a current-mode circuit, was designed using 0.18-um CMOS technology. Simulation results show that the frequency range of this 5-stage oscillator is 3.87 GHz to 5.81 GHz. The phase noise is −113.2 dBc/Hz at 1 MHz offset with a center frequency of 5.81 GHz. The performance of this new design shows improvement, in general, about 50 on the frequency while 15 on the phase noise, when compared with other non-LC tank topologies. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.