A 4.2-to-5.6 GHz Transformer-Based PMOS-only Stacked-gm VCO in 28-nm CMOS

This paper presents a low power, low phase noise, and small chip area transformer-based PMOS-only stacked-g», LC VCO in a 28-nm process. Both the top and bottom use PMOS cross-coupled pairs to provide negative resistances with suppressing the flicker noise. An interleaved transformer is used to get a higher coupling coefficient to achieve small chip area and high passive voltage gain. The VCO exhibits a wide turning range from 4.2 to 5.6 GHz, and low phase noise from -120 dBc/Hz to -113 dBc/Hz at 1MHz frequency offset, respectively. It consumes minimum 678 μ W and maximum 680 μ W from a 0.8V supply voltage which does not require internal LDO or DC-DC converter to reduce the supply voltage.