CMOS 1.98–5.58 GHz transformer‐based VCO with current‐reused topology

Abstract

A fully integrated ultra-wideband voltage-controlled-oscillator (VCO) constructed in a current-reused configuration is proposed. An ultrawide tuning range is achieved thanks to the adopted transformerbased resonator, which makes use of the transformer and the proper arrangement of capacitors, while the current-reused topology can dramatically save DC power consumption. The transformer layout has been properly designed to attain a die area comparable to a single inductor VCO. Fabricated in a 0.18 µm CMOS technology, the VCO provides a frequency tuning range as high as 95% from 1.98 to 5.58 GHz and exhibits a phase noise of −122.8 to −108.6 dBc/Hz at 1 MHz offset from the carrier across the entire frequency range. The VCO core consumes 5.6-7.2 mA of current from a 1.8 V supply and occupies approximately an area of 0.8 mm 2. Despite the ultrawide tuning range, the proposed VCO has the outstanding figure-ofmerit (FOM T) of −192 to −199 dBc/Hz.

A K‐band low phase noise and low power CMOS voltage‐controlled oscillator

“…The transformer feedback VCOs have been widely presented in the past . Compared to the traditional inductance‐capacitance (LC) VCO, transformer feedback technique can enlarge the output swing of the VCO at low voltage supply.…”