A 25–37GHz VCO Employing Stacked-Coupled Switched Inductor and Co-Tuned Buffer in 55nm CMOS for Multi-Band 5G mmW Applications

This paper presents a mmW voltage-controlled oscillator (VCO) employing stacked-coupled switched differential inductor (SSDI) and hybrid analog-digital varactor array (HVA) to simultaneously achieve wide tuning range and low phase noise. A frequency co-tuned VCO buffer is also developed to minimize the VCO output power variation. Fabricated in a 55-nm CMOS process, the VCO achieves an ultra-wide frequency tuning range of 41.14% (24.48 to 37.16 GHz) and a low phase noise of -124.91 dBc/Hz at 10 MHz offset. The FoMT is -192.67 dBc/Hz and the output power variation is less than 3 dB over the entire tuning range.