A 28 GHz SiGe QVCO and divider for an 81–86 GHz E-band beam steering transmitter PLL

This paper presents a QVCO and divider for a 28 GHz SiGe PLL. It was designed in a SiGe process with f_T= 200 GHz. The PLL is intended to be used for beam steering in an 81-86 GHz E-band transmitter. Phase control is implemented by programmable current injection into the loop filter. The simulations in Spectre use a layout extracted view with parasitics for the QVCO and the frequency divider and an ADS Momentum model for the QVCO inductors. The divider is implemented with four cascaded current-mode-logic (CML) blocks, for a reference frequency of 1.75 GHz. The low frequency parts of the PLL were represented with either Verilog-A or schematic models. The phase noise of the QVCO equals -105 dBc/Hz at 1MHz offset, while at the same offset the divider standalone has an input referred phase noise of -110 dBc/Hz. The phase control has been verified by transient simulations showing a phase control sensitivity of 1.5°/μA over a range exceeding 360°. With a supply of 1.5 V the QVCO and divider consumes 29 mA.