A 7.9-14.3GHz -243.3dB FoMT Sub-Sampling PLL with Transformer-Based Dual-Mode VCO in 40nm CMOS

The rapid development of modern wireless communication systems call for high quality frequency synthesizers. Microwave and 5G mm-wave communication require low jitter and wide frequency range synthesizers. This paper presents a 135fsrms jitter, 7.9-14.3GHz PLL integrated with a wide-band dual-mode VCO, as shown in Fig.1. Subsampling technique [1] is used to achieve ultra-low in-band phase noise. The dual-mode VCO is based on an “8”-shaped coil transformer and the resonant tank has balanced impedance at each mode. Compared with previous multi-mode VCOs, the proposed VCO shows identical performance at the two modes and PLL achieves low jitter across all frequency bands.