A 10 Gb/s, 120 GHz Compact and Energy-Efficient Harmonic-OOK Modulator using 90 nm SiGe BiCMOS

This paper presents a compact and energy-efficient frequency multiplier with an embedded direct-digital harmonic on-off keying modulator. The multiplier uses a standing-wave resonator (SWR), features a half-wavelength varactor-loaded transmission line for efficient harmonic generation. Additionally, a novel OOK modulation technique has also been introduced, which modulates by switching a non-uniform impedance coupled line (NUiCL) filter, integrated with the frequency multiplier. The proposed modulator exhibits data rate of $10 \mathrm{~Gb} / \mathrm{s}$ with bit-errorrate (BER) of less than $10^{-9}$. The proposed harmonic modulator, fabricated using 90 nm Silicon-Germanium (SiGe) BiCMOS technology process, is purely passive. Nevertheless, it features a single stage buffer amplifier which consumes only 4 mW of DC power ($\mathrm{P}_{\mathrm{DC}}$), resulting in an 8 dB conversion loss. The proposed circuit occupies a compact active area of $185 \mu \mathrm{~m} \times 350 \mu \mathrm{~m} \mathbf{(0. 0 6 5}$ $\mathbf{m m}^{2}$).