A 0.56 THz Phase-Locked Frequency Synthesizer in 65 nm CMOS Technology

This paper presents the design and characterization of a 0.56 THz frequency synthesizer implemented in standard 65 nm CMOS technology. Its front end consists of triple-push Colpitts oscillators (TPCOs), followed by the first and second stage injection locking frequency dividers (ILFDs) and a divide-by-16 chain. TPCOs are used to triple their fundamental frequencies to 0.53-0.56 THz, while ILFDs and the subsequent divider chain are used to divide such frequencies to 2.7-2.9 GHz. Its back end consists of separate frequency and phase-locked loops with unique CMOS circuit designs to accomplish the desirable frequency/phase locking, including: 1) band-selection inductor switches; 2) simultaneous bulk voltage tuning over TPCOs and the first ILFD; and 3) a dual port injection architecture for the first ILFD. The resultant prototype realizes a 21 GHz frequency locking range with phase noise lower than -74 dBc/Hz at 1 MHz offset, and consumes 174 mW dc power.