Analysis and Design Considerations for Achieving the Fundamental Limits of Phase Noise in mmWave Oscillators with On-Chip MEMS Resonator

TL;DR

This paper presents analysis and design strategies to minimize phase noise in 30 GHz on-chip MEMS resonator oscillators, overcoming high static capacitance issues at mmWave frequencies, validated through simulation.

Contribution

It introduces a general solution and design techniques for achieving ultra-low phase noise and high FoM in mmWave MEMS oscillators, addressing the challenge of small electromechanical coupling.

Findings

Achieved phase noise of -132 dBc/Hz at 1 MHz offset

Realized FoM of 217 dBc/Hz at 30 GHz

Validated with 14 nm GF technology design and simulation

Abstract

Very small electromechanical coupling coefficient in micro-electromechanical systems (MEMS) or acoustic resonators is quite of a concern for oscillator performance, specially at mmWave frequencies. This small coefficient is the manifestation of the small ratio of motional capacitance to static capacitance in the resonators. This work provides a general solution to overcome the problem of relatively high static capacitance at mmWave frequencies and presents analysis and design techniques for achieving extremely low phase noise and a very high figure-of-merit (FoM) in an on-chip MEMS resonator based mmWave oscillator. The proposed analysis and techniques are validated with design and simulation of a 30 GHz oscillator with MEMS resonator having quality factor of 10,000 in 14 nm GF technology. Post layout simulation results show that it achieves a phase noise of -132 dBc/Hz and FoM of 217 dBc/Hz at offset of 1 MHz.