A 5.1-to-7.3 mW, 2.4-to-5 GHz Class-C Mode-Switching Single-Ended-Complementary VCO Achieving >190 dBc/Hz FoM

Abstract

This brief reports a class-C mode-switching single-ended-complementary (MS-SEC) VCO for wideband operation. Unlike the existing wideband VCOs that utilize nMOS-only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-\text{g}_{\text{m}}$ </tex-math></inline-formula> transistors operating in the class-B mode to maximize the oscillation amplitude, our MS-SEC VCO combines the advantages of class-C mode, which delivers a tall current pulse, together with current-reuse to maximize the current efficiency while lowering the phase noise (PN). The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-{g}_{m}$ </tex-math></inline-formula> transistors are preserved within the saturation region to avoid the inherent trade-off between PN and power consumption for a wideband VCO, as well as the reliability concerns. The VCO prototyped in 130-nm CMOS occupies a die area of 0.33 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and consumes 5.1-to-7.3 mW at 1.2 V, while covering 2.4-to-5 GHz and meeting the stringent PN specification of the GSM standard with no SAW filter. The results correspond to a figure-of-merit of >190 dBc/Hz throughout the tuning range.