In this paper, low phase-noise, low-power, and compact oscillators are demonstrated at the millimeter-wave region based on differential transmission lines (DTLs) loaded with metamaterial resonators. There are two types of metamaterial resonators explored: split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs). By creating a sharp stopband at the resonance frequency from a loaded SRR or CSRR, the backward electrical-magnetic (EM) wave is reflected to couple with the forward EM wave to form a standing EM wave in the DTL host, which results in a high-Q and low-loss millimeter-wave resonator with stable EM energy stored. The resulting DTL-SRR and DTL-CSRR resonators are deployed for designs of millimeter-wave oscillators in 65-nm CMOS. The measurement results show that one DTL-SRR-based oscillator works at 76 GHz with power consumption of 2.7 mW, phase noise of -108.8 dBc/Hz at 10-MHz offset, and figure-of-merit (FOM) of -182.1 dBc/Hz , which is 4 dB better than that of a 76-GHz standing-wave oscillator implemented on the same chip. Moreover, another DTL-CSRR-based oscillator works at 96 GHz with power consumption of 7.5 mW. Compared to the existing oscillators with an LC-tank-based resonator, the DTL-CSRR oscillator has much lower phase noise of -111.5 dBc/Hz at 10-MHz offset and a FOM of -182.4 dBc/Hz.

MOE (Min. of Education, S’pore)