A Novel Direct-Binary Amplitude Modulator Integrated with a 16-Times Frequency Multiplier for 5G+ Applications

Abstract

This article presents a novel passive direct binary amplitude modulator (AM) integrated with two frequency multipliers (FMs) and a drive amplifier. Both FMs are composed of a harmonic generator and a modified cascode buffer, along with an additional single-to-differential amplifier added in front of the first FM. The input frequency band (1.5–1.75 GHz) is up-converted to the intermediate frequency band of 4–5 GHz by the first FM, while the second FM up-converts the IF band to the target millimeter wave band of 24–28 GHz. Furthermore, the mm-wave amplitude is directly modulated by a capacitor ladder whose ratio is digitally programmable. This unique capacitor-ladder structure AM is employed to attain uniformly distributed constellation points and improve the output signal-to-noise ratio. The proposed modulator is fabricated on a 65-nm CMOS with a die size of 0.73 mm<sup>2</sup>. When applying the modulator to I/Q paths, 1.33% error vector magnitude for 256-QAM was measured at 26 GHz.