Flicker Noise Upconversion and Reduction Mechanisms in RF/Millimeter-Wave Oscillators for 5G Communications

The fifth generation (5G) cellular communications in millimeter-wave (mmW) bands (e.g., 28GHz) place very tough requirements on phase noise (PN) of local oscillators (LO). However, in the advanced CMOS technology (e.g., 28nm, 16nm, 7nm, ...), the intrinsic 1/f current noise of MOS transistor is increasingly worsening. It could adversely affect the PN of the LO significantly, especially the flicker PN, leading to a very high 1/f3 PN corner (usually exceeding 1 MHz), which is difficult to be attenuated by a mmW PLL. On the other hand, the current literature is full of conflicts and confusing theories about the flicker noise upconversion, with a large number of ambiguities in the RF range, let alone in the mmW range. Thus, lowering the 1/f3 PN and figuring out its actual mechanisms are highly desired for 5G mmW communications.