Frequency Generation Toward Sub-THz: Design Considerations and Circuit Techniques

As wireless communication, sensing, and radar systems evolve toward mm-wave and sub-THz frequencies, frequency generation has emerged as one of the most critical and challenging building blocks. In this regime, conventional design assumptions made at RF frequencies no longer hold due to limited transistor gain, increased parasitics, reduced quality factors, and stringent power and area constraints. Consequently, achieving low phase noise, wide frequency coverage, and robust scalability requires careful consideration of both architectural choices and circuit-level techniques. This talk provides a structured overview of frequency generation toward sub-THz, emphasizing key design considerations that govern oscillator and frequency-multiplier performance. Fundamental trade-offs among phase noise, power consumption, tuning range, and silicon area are discussed, followed by an examination of practical circuit techniques used to mitigate noise and efficiency degradation at high frequencies. The presentation covers LC-based oscillators, injection-locked architectures, and harmonic- generation-based frequency multipliers, highlighting how their operating principles and limitations evolve as frequency scales toward sub-THz.