Design and analysis of D-Band on-chip modulator and signal source based on split-ring resonator

Abstract

In an effort towards high-speed and low-power I/O data link in future Exa-scale data server, this paper presents a signal source and a modulator in D-band. Split-ring resonator (SRR) structures are used in both to boost the signal power and extinction ratio (ER). The modulator manifests itself as a compact SRR whose magnetic resonance frequency can be modulated by high speed data. Such a magnetic metamaterial achieves a significant reduction of radiation loss with high ER by stacking two auxiliary SRR unit-cells with interleaved placement. The high-Q tank for oscillation is realized by a stacked SRR decorated with slow-wave transmission line (T-line) for electric field confinement. A 4-ways power combined fundamental 80-GHz coupled-oscillator-network is magnetically synchronized by the slow-wave T-line, which is frequency doubled to 160 GHz. Fabricated in 65-nm CMOS process, the measured results show that: 1) the modulator achieves 3 dB insertion loss at on-state with 43 dB isolation at off-state, leading to a 40-dB ER at 125 GHz within an area of only 40 μm × 67 μm. 2) The signal source achieves 6.3% frequency tuning range (FTR) with 3.7 mW peak output power at 160 GHz within 0.053 mm2 active area. It has a measured phase noise of –105 dBc/Hz at 10 MHz offset, 5.5% DC-to-RF power efficiency, 70.1 mW/mm2 power density, FOM of –171 dBc/Hz and FOMT of –172.7 dBc/Hz.