A 1.1-V CMOS frequency synthesizer with pass-transistor-logic prescaler for U-NII band system

This paper presents a 1.1-V low-voltage frequency synthesizer for U-NII band system. In order to achieve low-voltage and high-speed operations, a new 32/33 dual-modulus prescaler with pass-transistor-logic (PTL) topology and folding-injection architecture is proposed. Fabricated in 0.18-μm CMOS technology, the measured phase noise of the 6.08-GHz frequency synthesizer at a 1MHz offset is −114dBc/Hz and the reference spur at an offset of 5MHz is less than 61dBc. The settling time within 20ppm after 640MHz jump (widest jump from low band to high band) is less than 40μs. The frequency synthesizer dissipates 31mW from a 1.1-V supply and occupies a chip area of 1.3mm
²
.