A 0.35-mW 70-GHz Self-Resonant E-TSPC Frequency Divider With Backgate Adjustment

This research work presents the analysis, design, and characterization of a concept for an mm-wave divide-by-4 frequency divider utilizing an extended true single-phase clock (E-TSPC) and a TSPC divide-by-2 stage. The divider operates from 16 to 70 GHz from a 0.8-V supply with the highest power consumption of 0.35 mW. Operating frequencies up to 53 GHz were reached with a supply voltage of only 0.5 V at 0.12-mW power consumption. The self-resonance frequency of the circuit is adjustable through backgate biasing from 40 up to 70 GHz at 0.9-V supply, allowing a reduction in the required input power in this frequency range. Locking ranges up to 114% have been measured by changing only the backgate voltage. The circuit design is illustrated in detail and supported with original analysis and an explicit expression to calculate the self-oscillation frequency of the E-TSPC divider. The presented circuit was fabricated on a 22-nm fully depleted silicon-on-isolator complementary metal–oxide–semiconductor (CMOS) technology and occupies an active area of
$3.4 ~\mu \text{m}^{2}$
. The circuit requires the lowest power consumption and area among state-of-the-art RF frequency dividers, while it demonstrates the second widest adjustable operating frequency range and the second highest self-resonance frequency for CMOS D-flip-flop frequency dividers.